diff --git a/backend/services/tournamentService.js b/backend/services/tournamentService.js
index ec043f7..4109f9a 100644
--- a/backend/services/tournamentService.js
+++ b/backend/services/tournamentService.js
@@ -180,32 +180,52 @@ class TournamentService {
         // 2) Alte Matches löschen
         await TournamentMatch.destroy({ where: { tournamentId } });
 
-        // 3) Shuffle + verteilen
-        const shuffled = members.slice();
-        for (let i = shuffled.length - 1; i > 0; i--) {
-            const j = Math.floor(Math.random() * (i + 1));
-            [shuffled[i], shuffled[j]] = [shuffled[j], shuffled[i]];
+        // 3) Prüfe, ob Spieler bereits manuell zugeordnet wurden
+        const alreadyAssigned = members.filter(m => m.groupId !== null);
+        const unassigned = members.filter(m => m.groupId === null);
+        
+        if (alreadyAssigned.length > 0) {
+            // Spieler sind bereits manuell zugeordnet - nicht neu verteilen
+            console.log(`${alreadyAssigned.length} Spieler bereits zugeordnet, ${unassigned.length} noch nicht zugeordnet`);
+        } else {
+            // Keine manuellen Zuordnungen - zufällig verteilen
+            const shuffled = members.slice();
+            for (let i = shuffled.length - 1; i > 0; i--) {
+                const j = Math.floor(Math.random() * (i + 1));
+                [shuffled[i], shuffled[j]] = [shuffled[j], shuffled[i]];
+            }
+            groups.forEach((g, idx) => {
+                shuffled
+                    .filter((_, i) => i % groups.length === idx)
+                    .forEach(m => m.update({ groupId: g.id }));
+            });
         }
-        groups.forEach((g, idx) => {
-            shuffled
-                .filter((_, i) => i % groups.length === idx)
-                .forEach(m => m.update({ groupId: g.id }));
-        });
 
-        // 4) Round‑Robin anlegen wie gehabt
+        // 4) Round‑Robin anlegen wie gehabt - NUR innerhalb jeder Gruppe
         for (const g of groups) {
             const gm = await TournamentMember.findAll({ where: { groupId: g.id } });
+            if (gm.length < 2) {
+                console.warn(`Gruppe ${g.id} hat nur ${gm.length} Teilnehmer - keine Matches erstellt`);
+                continue;
+            }
             const rounds = this.generateRoundRobinSchedule(gm);
             for (let roundIndex = 0; roundIndex < rounds.length; roundIndex++) {
                 for (const [p1Id, p2Id] of rounds[roundIndex]) {
-                    await TournamentMatch.create({
-                        tournamentId,
-                        groupId: g.id,
-                        round: 'group',
-                        player1Id: p1Id,
-                        player2Id: p2Id,
-                        groupRound: roundIndex + 1
-                    });
+                    // Prüfe, ob beide Spieler zur gleichen Gruppe gehören
+                    const p1 = gm.find(p => p.id === p1Id);
+                    const p2 = gm.find(p => p.id === p2Id);
+                    if (p1 && p2 && p1.groupId === p2.groupId && p1.groupId === g.id) {
+                        await TournamentMatch.create({
+                            tournamentId,
+                            groupId: g.id,
+                            round: 'group',
+                            player1Id: p1Id,
+                            player2Id: p2Id,
+                            groupRound: roundIndex + 1
+                        });
+                    } else {
+                        console.warn(`Spieler gehören nicht zur gleichen Gruppe: ${p1Id} (${p1?.groupId}) vs ${p2Id} (${p2?.groupId}) in Gruppe ${g.id}`);
+                    }
                 }
             }
         }
diff --git a/frontend/src/views/TournamentsView.vue b/frontend/src/views/TournamentsView.vue
index 0b3da5e..be980b0 100644
--- a/frontend/src/views/TournamentsView.vue
+++ b/frontend/src/views/TournamentsView.vue
@@ -24,34 +24,41 @@
                 <span>Spielen in Gruppen</span>
             </label>
             <section class="participants">
-                <h4>Teilnehmer</h4>
-                <ul>
-                    <li v-for="participant in participants" :key="participant.id">
-                        {{ participant.member.firstName }}
-                        {{ participant.member.lastName }}
-                        <template v-if="isGroupTournament">
-                            <label class="inline-label">
-                                Gruppe:
-                                <select v-model.number="participant.groupNumber">
-                                    <option :value="null">–</option>
-                                    <option v-for="group in groups" :key="group.groupId" :value="group.groupNumber">
-                                        Gruppe {{ group.groupNumber }}
-                                    </option>
-                                </select>
-                            </label>
-                        </template>
-                        <button @click="removeParticipant(participant)" style="margin-left:0.5rem" class="trash-btn">
-                            🗑️
-                        </button>
-                    </li>
-                </ul>
-                <select v-model="selectedMember">
-                    <option v-for="member in clubMembers" :key="member.id" :value="member.id">
-                        {{ member.firstName }}
-                        {{ member.lastName }}
-                    </option>
-                </select>
-                <button @click="addParticipant">Hinzufügen</button>
+                <div class="participants-header" @click="toggleParticipants">
+                    <h4>Teilnehmer</h4>
+                    <span class="collapse-icon" :class="{ 'expanded': showParticipants }">▼</span>
+                </div>
+                <div v-show="showParticipants" class="participants-content">
+                    <ul>
+                        <li v-for="participant in participants" :key="participant.id">
+                            {{ participant.member?.firstName || 'Unbekannt' }}
+                            {{ participant.member?.lastName || '' }}
+                            <template v-if="isGroupTournament">
+                                <label class="inline-label">
+                                    Gruppe:
+                                    <select v-model.number="participant.groupNumber" @change="updateParticipantGroup(participant, $event)">
+                                        <option :value="null">–</option>
+                                        <option v-for="group in groups" :key="group.groupId" :value="group.groupNumber">
+                                            Gruppe {{ group.groupNumber }}
+                                        </option>
+                                    </select>
+                                </label>
+                            </template>
+                            <button @click="removeParticipant(participant)" style="margin-left:0.5rem" class="trash-btn">
+                                🗑️
+                            </button>
+                        </li>
+                    </ul>
+                    <div class="add-participant">
+                        <select v-model="selectedMember">
+                            <option v-for="member in clubMembers" :key="member.id" :value="member.id">
+                                {{ member.firstName }}
+                                {{ member.lastName }}
+                            </option>
+                        </select>
+                        <button @click="addParticipant">Hinzufügen</button>
+                    </div>
+                </div>
             </section>
             <section v-if="isGroupTournament" class="group-controls">
                 <label>
@@ -78,22 +85,38 @@
                     <table>
                         <thead>
                             <tr>
-                                <th>Platz</th>
+                                <th>Index</th>
                                 <th>Spieler</th>
                                 <th>Punkte</th>
                                 <th>Satz</th>
                                 <th>Diff</th>
+                                <th v-for="(opponent, idx) in groupRankings[group.groupId]" :key="`opp-${opponent.id}`">
+                                    G{{ String.fromCharCode(96 + group.groupNumber) }}{{ idx + 1 }}
+                                </th>
+                                <th>Platz</th>
                             </tr>
                         </thead>
                         <tbody>
-                            <tr v-for="pl in groupRankings[group.groupId]" :key="pl.id">
-                                <td>{{ pl.position }}.</td>
+                            <tr v-for="(pl, idx) in groupRankings[group.groupId]" :key="pl.id">
+                                <td><strong>G{{ String.fromCharCode(96 + group.groupNumber) }}{{ idx + 1 }}</strong></td>
                                 <td>{{ pl.name }}</td>
                                 <td>{{ pl.points }}</td>
                                 <td>{{ pl.setsWon }}:{{ pl.setsLost }}</td>
                                 <td>
                                     {{ pl.setDiff >= 0 ? '+' + pl.setDiff : pl.setDiff }}
                                 </td>
+                                <td v-for="(opponent, oppIdx) in groupRankings[group.groupId]" 
+                                    :key="`match-${pl.id}-${opponent.id}`"
+                                    :class="['match-cell', { 'clickable': idx !== oppIdx }]"
+                                    @click="idx !== oppIdx ? highlightMatch(pl.id, opponent.id, group.groupId) : null">
+                                    <span v-if="idx === oppIdx" class="diagonal"></span>
+                                    <span v-else-if="getMatchLiveResult(pl.id, opponent.id, group.groupId)" 
+                                          :class="getMatchCellClasses(pl.id, opponent.id, group.groupId)">
+                                        {{ getMatchDisplayText(pl.id, opponent.id, group.groupId) }}
+                                    </span>
+                                    <span v-else class="no-match">-</span>
+                                </td>
+                                <td>{{ pl.position }}.</td>
                             </tr>
                         </tbody>
                     </table>
@@ -122,7 +145,7 @@
                     </tr>
                 </thead>
                 <tbody>
-                    <tr v-for="m in groupMatches" :key="m.id">
+                    <tr v-for="m in groupMatches" :key="m.id" :data-match-id="m.id">
                         <td>{{ m.groupRound }}</td>
                         <td>{{ m.groupNumber }}</td>
                         <td>
@@ -301,6 +324,7 @@ export default {
             groups: [],
             matches: [],
             showKnockout: false,
+            showParticipants: false, // Kollaps-Status für Teilnehmerliste
             editingResult: {
                 matchId: null,   // aktuell bearbeitetes Match
                 set: null,   // aktuell bearbeitete Satz‑Nummer
@@ -369,6 +393,15 @@ export default {
             return rankings;
         },
 
+        // Mapping von groupId zu groupNumber für die Teilnehmer-Auswahl
+        groupIdToNumberMap() {
+            const map = {};
+            this.groups.forEach(g => {
+                map[g.groupId] = g.groupNumber;
+            });
+            return map;
+        },
+
         rankingList() {
             const finalMatch = this.knockoutMatches.find(
                 m => m.round.toLowerCase() === 'finale'
@@ -435,6 +468,20 @@ export default {
         );
         this.clubMembers = m.data;
     },
+    mounted() {
+        // Event-Listener für das Entfernen des Highlights
+        document.addEventListener('click', (e) => {
+            // Entferne Highlight nur wenn nicht auf eine Matrix-Zelle geklickt wird
+            if (!e.target.closest('.match-cell')) {
+                this.clearHighlight();
+            }
+        });
+        
+        // Event-Listener für Eingabefelder
+        document.addEventListener('input', () => {
+            this.clearHighlight();
+        });
+    },
     methods: {
         normalizeResultInput(raw) {
             const s = raw.trim();
@@ -493,11 +540,27 @@ export default {
                 m[g.groupId] = g.groupNumber;
                 return m;
             }, {});
-            this.matches = mRes.data.map(m => ({
-                ...m,
-                groupNumber: grpMap[m.groupId] || 0,
-                resultInput: ''
-            }));
+            
+            this.matches = mRes.data.map(m => {
+                // Bestimme groupId basierend auf den Spielern, da die Matches groupId: null haben
+                const player1GroupId = m.player1?.groupId;
+                const player2GroupId = m.player2?.groupId;
+                const matchGroupId = player1GroupId || player2GroupId;
+                
+                return {
+                    ...m,
+                    groupId: matchGroupId, // Überschreibe null mit der korrekten groupId
+                    groupNumber: grpMap[matchGroupId] || 0,
+                    resultInput: ''
+                };
+            });
+            
+            // Initialisiere groupNumber für Teilnehmer basierend auf groupId
+            this.initializeParticipantGroupNumbers();
+            
+            // Setze Kollaps-Status: ausgeklappt wenn keine Spiele, eingeklappt wenn Spiele vorhanden
+            this.showParticipants = this.matches.length === 0;
+            
             this.showKnockout = this.matches.some(m => m.round !== 'group');
         },
 
@@ -785,6 +848,207 @@ export default {
             } catch (err) {
                 alert('Fehler beim Zurücksetzen der K.o.-Runde');
             }
+        },
+
+        getMatchResult(player1Id, player2Id, groupId) {
+            const match = this.matches.find(m => 
+                m.round === 'group' && 
+                m.groupId === groupId &&
+                ((m.player1.id === player1Id && m.player2.id === player2Id) ||
+                 (m.player1.id === player2Id && m.player2.id === player1Id)) &&
+                m.isFinished
+            );
+            
+            if (!match) return null;
+            
+            // Bestimme, wer gewonnen hat
+            const [sets1, sets2] = match.result.split(':').map(n => +n);
+            const player1Won = sets1 > sets2;
+            
+            // Gib das Ergebnis in der Sicht des ersten Spielers zurück
+            if (match.player1.id === player1Id) {
+                return player1Won ? 'W' : 'L';
+            } else {
+                return player1Won ? 'L' : 'W';
+            }
+        },
+
+        getMatchLiveResult(player1Id, player2Id, groupId) {
+            const match = this.matches.find(m => 
+                m.round === 'group' && 
+                m.groupId === groupId &&
+                ((m.player1.id === player1Id && m.player2.id === player2Id) ||
+                 (m.player1.id === player2Id && m.player2.id === player1Id))
+            );
+            
+            if (!match) return null;
+            
+            // Berechne aktuelle Sätze aus tournamentResults
+            let sets1 = 0, sets2 = 0;
+            if (match.tournamentResults && match.tournamentResults.length > 0) {
+                match.tournamentResults.forEach(result => {
+                    if (result.pointsPlayer1 > result.pointsPlayer2) {
+                        sets1++;
+                    } else if (result.pointsPlayer2 > result.pointsPlayer1) {
+                        sets2++;
+                    }
+                });
+            }
+            
+            // Bestimme die Anzeige basierend auf der Spieler-Reihenfolge
+            if (match.player1.id === player1Id) {
+                return {
+                    sets1: sets1,
+                    sets2: sets2,
+                    isFinished: match.isFinished,
+                    player1Won: sets1 > sets2,
+                    player2Won: sets2 > sets1,
+                    isTie: sets1 === sets2
+                };
+            } else {
+                return {
+                    sets1: sets2,
+                    sets2: sets1,
+                    isFinished: match.isFinished,
+                    player1Won: sets2 > sets1,
+                    player2Won: sets1 > sets2,
+                    isTie: sets1 === sets2
+                };
+            }
+        },
+
+        highlightMatch(player1Id, player2Id, groupId) {
+            console.log('highlightMatch called:', { player1Id, player2Id, groupId });
+            
+            // Finde das entsprechende Match (auch unbeendete)
+            const match = this.matches.find(m => 
+                m.round === 'group' && 
+                m.groupId === groupId &&
+                ((m.player1.id === player1Id && m.player2.id === player2Id) ||
+                 (m.player1.id === player2Id && m.player2.id === player1Id))
+            );
+            
+            console.log('Found match:', match);
+            
+            if (!match) {
+                console.log('No match found');
+                return;
+            }
+            
+            // Setze Highlight-Klasse
+            this.$nextTick(() => {
+                const matchElement = document.querySelector(`tr[data-match-id="${match.id}"]`);
+                console.log('Match element:', matchElement);
+                
+                if (matchElement) {
+                    // Entferne vorherige Highlights
+                    document.querySelectorAll('.match-highlight').forEach(el => {
+                        el.classList.remove('match-highlight');
+                    });
+                    
+                    // Füge Highlight hinzu
+                    matchElement.classList.add('match-highlight');
+                    
+                    // Scrolle zum Element
+                    matchElement.scrollIntoView({ 
+                        behavior: 'smooth', 
+                        block: 'center' 
+                    });
+                } else {
+                    console.log('Match element not found in DOM');
+                }
+            });
+        },
+
+        clearHighlight() {
+            // Entferne alle Highlights
+            document.querySelectorAll('.match-highlight').forEach(el => {
+                el.classList.remove('match-highlight');
+            });
+        },
+
+        async updateParticipantGroup(participant, event) {
+            const groupNumber = parseInt(event.target.value);
+            
+            // Aktualisiere lokal
+            participant.groupNumber = groupNumber;
+            
+            // Bereite alle Teilnehmer-Zuordnungen vor
+            const assignments = this.participants.map(p => ({
+                participantId: p.id,
+                groupNumber: p.groupNumber || null
+            }));
+            
+            // Sende an Backend
+            try {
+                await apiClient.post('/tournament/groups/manual', {
+                    clubId: this.currentClub,
+                    tournamentId: this.selectedDate,
+                    assignments: assignments,
+                    numberOfGroups: this.numberOfGroups,
+                    maxGroupSize: this.maxGroupSize
+                });
+                
+                // Lade Daten neu, um die aktualisierten Gruppen zu erhalten
+                await this.loadTournamentData();
+            } catch (error) {
+                console.error('Fehler beim Aktualisieren der Gruppe:', error);
+                // Bei Fehler: Lade Daten neu
+                await this.loadTournamentData();
+            }
+        },
+
+        // Initialisiere groupNumber basierend auf groupId
+        initializeParticipantGroupNumbers() {
+            this.participants.forEach(participant => {
+                if (participant.groupId) {
+                    const group = this.groups.find(g => g.groupId === participant.groupId);
+                    if (group) {
+                        participant.groupNumber = group.groupNumber;
+                    }
+                }
+            });
+        },
+
+        toggleParticipants() {
+            this.showParticipants = !this.showParticipants;
+        },
+
+        getMatchDisplayText(player1Id, player2Id, groupId) {
+            const liveResult = this.getMatchLiveResult(player1Id, player2Id, groupId);
+            if (!liveResult) return '-';
+            
+            // Zeige Satzergebnis (z.B. 1:0, 2:1, 0:2)
+            return `${liveResult.sets1}:${liveResult.sets2}`;
+        },
+
+        getMatchCellClasses(player1Id, player2Id, groupId) {
+            const liveResult = this.getMatchLiveResult(player1Id, player2Id, groupId);
+            if (!liveResult) return ['no-match'];
+            
+            const classes = ['match-result'];
+            
+            if (liveResult.isFinished) {
+                // Spiel beendet: Dunkle Farben
+                if (liveResult.player1Won) {
+                    classes.push('match-finished-win');
+                } else if (liveResult.player2Won) {
+                    classes.push('match-finished-loss');
+                } else {
+                    classes.push('match-finished-tie');
+                }
+            } else {
+                // Spiel läuft: Helle Farben
+                if (liveResult.player1Won) {
+                    classes.push('match-live-win');
+                } else if (liveResult.player2Won) {
+                    classes.push('match-live-loss');
+                } else {
+                    classes.push('match-live-tie');
+                }
+            }
+            
+            return classes;
         }
     }
 };
@@ -822,4 +1086,173 @@ td {
 button {
     margin-left: 0.5em;
 }
+
+.diagonal {
+    background-color: #000;
+    color: #000;
+    display: block;
+    width: 100%;
+    height: 100%;
+    min-height: 20px;
+}
+
+.match-result {
+    font-weight: bold;
+    padding: 2px 4px;
+    border-radius: 3px;
+}
+
+.match-result.win {
+    background-color: #d4edda;
+    color: #155724;
+}
+
+.match-result.loss {
+    background-color: #f8d7da;
+    color: #721c24;
+}
+
+/* Live-Ergebnisse während des Spiels */
+.match-live-win {
+    background-color: #d1eca1; /* Hellgrün */
+    color: #0c5460;
+    font-weight: bold;
+}
+
+.match-live-loss {
+    background-color: #ffeaa7; /* Orange */
+    color: #d63031;
+    font-weight: bold;
+}
+
+.match-live-tie {
+    background-color: #f8f9fa; /* Neutral */
+    color: #6c757d;
+    font-weight: bold;
+}
+
+/* Beendete Spiele */
+.match-finished-win {
+    background-color: #28a745; /* Dunkelgrün */
+    color: white;
+    font-weight: bold;
+}
+
+.match-finished-loss {
+    background-color: #fd7e14; /* Dunkelorange */
+    color: white;
+    font-weight: bold;
+}
+
+.match-finished-tie {
+    background-color: #6c757d; /* Grau */
+    color: white;
+    font-weight: bold;
+}
+
+/* Kollabierbare Teilnehmerliste */
+.participants-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    cursor: pointer;
+    padding: 0.5rem 0;
+    border-bottom: 1px solid #dee2e6;
+    margin-bottom: 1rem;
+}
+
+.participants-header:hover {
+    background-color: #f8f9fa;
+    border-radius: 4px;
+}
+
+.participants-header h4 {
+    margin: 0;
+    color: #495057;
+}
+
+.collapse-icon {
+    font-size: 0.8em;
+    color: #6c757d;
+    transition: transform 0.3s ease;
+    user-select: none;
+}
+
+.collapse-icon.expanded {
+    transform: rotate(180deg);
+}
+
+.participants-content {
+    animation: slideDown 0.3s ease;
+}
+
+@keyframes slideDown {
+    from {
+        opacity: 0;
+        max-height: 0;
+    }
+    to {
+        opacity: 1;
+        max-height: 1000px;
+    }
+}
+
+.add-participant {
+    margin-top: 1rem;
+    padding-top: 1rem;
+    border-top: 1px solid #dee2e6;
+    display: flex;
+    gap: 0.5rem;
+    align-items: center;
+}
+
+.no-match {
+    color: #ccc;
+}
+
+.group-table table {
+    font-size: 0.9em;
+}
+
+.group-table th,
+.group-table td {
+    padding: 0.3em 0.5em;
+    text-align: center;
+}
+
+.group-table th:first-child,
+.group-table td:first-child {
+    text-align: left;
+    font-weight: bold;
+}
+
+.group-table th:nth-child(2),
+.group-table td:nth-child(2) {
+    text-align: left;
+    min-width: 120px;
+}
+
+.match-cell.clickable {
+    cursor: pointer;
+    transition: all 0.2s ease;
+    position: relative;
+}
+
+.match-cell.clickable:hover {
+    background-color: #f8f9fa;
+    transform: scale(1.02);
+    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
+}
+
+.match-highlight {
+    background-color: #fff3cd !important;
+    border: 2px solid #ffc107 !important;
+    animation: highlight-pulse 0.5s ease-in-out;
+}
+
+@keyframes highlight-pulse {
+    0% { transform: scale(1); }
+    50% { transform: scale(1.02); }
+    100% { transform: scale(1); }
+}
 </style>
\ No newline at end of file