diff --git a/src/main/java/nl/connectedit/swiss/mapper/TournamentMapper.java b/src/main/java/nl/connectedit/swiss/mapper/TournamentMapper.java
index 9e34731..2fb50a2 100644
--- a/src/main/java/nl/connectedit/swiss/mapper/TournamentMapper.java
+++ b/src/main/java/nl/connectedit/swiss/mapper/TournamentMapper.java
@@ -94,13 +94,15 @@ public class TournamentMapper implements DtoMapper<Tournament, TournamentDto>, E
     var playersCounting = new ArrayList<Long>();
 
     for (var event : tournament.getEvents()) {
-      for (var group : event.getGroups()) {
-        for (var round : group.getRounds()) {
-          for (var match : round.getMatches()) {
-            if (match.getStatus() == Status.IN_PROGRESS && match.getCounter() != null) {
-              var counter = getTournamentPlayerFromPlayerId(tournament, match.getCounter().getId());
-              if (counter != null) {
-                playersCounting.add(counter.getId());
+      if (event.getGroups() != null) {
+        for (var group : event.getGroups()) {
+          for (var round : group.getRounds()) {
+            for (var match : round.getMatches()) {
+              if (match.getStatus() == Status.IN_PROGRESS && match.getCounter() != null) {
+                var counter = getTournamentPlayerFromPlayerId(tournament, match.getCounter().getId());
+                if (counter != null) {
+                  playersCounting.add(counter.getId());
+                }
               }
             }
           }
@@ -114,11 +116,13 @@ public class TournamentMapper implements DtoMapper<Tournament, TournamentDto>, E
     var playersPlaying = new ArrayList<Long>();
 
     for (var event : tournament.getEvents()) {
-      for (var group : event.getGroups()) {
-        for (var round : group.getRounds()) {
-          for (var match : round.getMatches()) {
-            if (match.getStatus() == Status.IN_PROGRESS) {
-              playersPlaying.addAll(getPlayersInMatch(tournament, match));
+      if (event.getGroups() != null) {
+        for (var group : event.getGroups()) {
+          for (var round : group.getRounds()) {
+            for (var match : round.getMatches()) {
+              if (match.getStatus() == Status.IN_PROGRESS) {
+                playersPlaying.addAll(getPlayersInMatch(tournament, match));
+              }
             }
           }
         }
@@ -129,6 +133,10 @@ public class TournamentMapper implements DtoMapper<Tournament, TournamentDto>, E
   }
 
   private List<Long> getPlayersAvailable(Tournament tournament) {
+    if (tournament.getTournamentPlayers() == null) {
+      return List.of();
+    }
+
     var playersAvailable = tournament.getTournamentPlayers()
       .stream()
       .map(TournamentPlayer::getId)