Connect 4 tournament

Question

I am implementing a 4 in a row in a tournament mode. First I implemented a round robin algorithm and the results are shown in a textbox. For example let says the number of players that are going to play are 4 then the tournament consists of:

Round 0:
0 v 3
1 v 2

Round 1:
0 v 1
2 v 3

Round 2:
0 v 2
1 v 3

When a game finishes the user presses the next game button and another game begins. My question is how can I determine the winner of everygame lets say 0 v 3 was won by 0 and 1 v 2 was won by 2. A messagebox should appear by saying player 0 for example has won. Also I would like that the player who has the most wins, wins the tournament. Thanks