diff --git a/pytron_run/utils.py b/pytron_run/utils.py
index c8ae7af..f0888d3 100644
--- a/pytron_run/utils.py
+++ b/pytron_run/utils.py
@@ -7,27 +7,69 @@ def run_battle(ai1, ai2, width, height):
     ai2_victories = 0
 
     for (initial_position_one, initial_position_two) in positions():
-        game = Game(width, height, [
-            PositionPlayer(1, ai1.constructor(), initial_position_one),
-            PositionPlayer(2, ai2.constructor(), initial_position_two),
-        ])
-        game.main_loop()
 
-        if game.winner == 1:
+        player_1 = None
+        player_2 = None
+
+        try:
+            player_1 = ai1.constructor()
+        except:
+            pass
+
+        try:
+            player_2 =  ai2.constructor()
+        except:
+            pass
+
+
+        winner = None
+        if player_1 is not None and player_2 is not None:
+            game = Game(width, height, [
+                PositionPlayer(1, player_1, initial_position_one),
+                PositionPlayer(2, player_2, initial_position_two),
+            ])
+            game.main_loop()
+            winner = game.winner
+        elif player_1 is None and player_2 is not None:
+            # Player 2 wins because he was able to build an ai...
+            winner = 2
+        elif player_1 is not None and player_2 is None:
+            winner = 1
+        else:
+            pass
+
+        if winner == 1:
             ai1_victories += 1
-        elif game.winner == 2:
+        elif winner == 2:
             ai2_victories += 1
 
         # Inverse positions and replay to be symmetrical
-        game = Game(width, height, [
-            PositionPlayer(1, ai2.constructor(), initial_position_one),
-            PositionPlayer(2, ai1.constructor(), initial_position_two),
-        ])
-        game.main_loop()
+        try:
+            player_2 = ai2.constructor()
+        except:
+            pass
 
-        if game.winner == 1:
+        try:
+            player_1 =  ai1.constructor()
+        except:
+            pass
+
+        winner = None
+        if player_1 is not None and player_2 is not None:
+            game = Game(width, height, [
+                PositionPlayer(1, player_2, initial_position_one),
+                PositionPlayer(2, player_1, initial_position_two),
+            ])
+            game.main_loop()
+            winner = game.winner
+        elif player_1 is None and player_2 is not None:
+            winner = 1
+        elif player_1 is not None and player_2 is None:
+            winner = 2
+
+        if winner == 1:
             ai2_victories += 1
-        elif game.winner == 2:
+        elif winner == 2:
             ai1_victories += 1
 
     return (ai1_victories, ai2_victories, 2 * games - ai1_victories - ai2_victories)