'Who do you wanna beat?' works. 'Who do you wanna win?' doesn't. Here's why.

English usually lets 'want to' shrink to 'wanna,' but not when an invisible trace left by a moved question word sits between them. 'Who do you want to beat?' contracts fine because 'who' is the object of 'beat'; 'Who do you want to win?' can't, because 'who' is the hidden subject of 'win.' Linguists use this gap you can't hear as evidence that unspoken sentence structure still shapes speech.

— Wikipedia contributors, Syntactic movement — Section on traces and wanna-contraction