diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Tournament.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Tournament.kt
index 2320d24..0e13819 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Tournament.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Tournament.kt
@@ -119,7 +119,7 @@ sealed class Tournament <P: Pairable>(
     }
 
     fun pairedPlayers() = games.flatMap { it.values }.flatMap { listOf(it.black, it.white) }.toSet()
-    fun hasPlayer(dbId: DatabaseId, pId: String) = players.values.filter { player -> pId == player.externalIds[dbId] }.isNotEmpty()
+    fun hasPlayer(dbId: DatabaseId, pId: String) = pId.isNotBlank() && players.values.filter { player -> pId == player.externalIds[dbId] }.isNotEmpty()
 }
 
 // standard tournament of individuals