A funny situation, I'll keep it in mind for the future. There's nothing you can do against match-fixing. The players could have done it more elegantly, but the result would have been the same. The moral of this story is: In the group stage, you need to play against weaker opponents, waiting for the leader to gain a critical advantage over the other participants in the group. After that, you can offer the leader a draw, which he will often agree to in order not to waste his time. That's what fair play looks like.