If you pray to God for your team to win, you need to ask yourself what kind of a god you believe in.
Is God really a cosmic genie that exists for the purpose of granting our wishes? If such a god grants my prayers for my team to win, is God rejecting the prayers for the other team? If so, why? Is it because I am special? If I am so special, how did I get to be that way? Am I the Chosen One? Or, does God perform an arithmetic function based on the number of one team's prayers minus the others? If so, then God is like a cosmic computer. Even more importantly, why does God need us to tell Him what to do? Is God so indecisive that He can't make up His mind which team to "let" win until He listens to some prayers, especially mine? If so, in a sense, that makes me more powerful than God, since I make up His mind for Him. And If I am more powerful than God, then who should be praying to whom in the first place?