break (someone's) serve
In tennis, to win a game that is being served by one's opponent. She broke her opponent's serve in the last game, and it looks like the match is now firmly in her control.
break someone's serve
In tennis and related sports, win a game served by one's opponent, as in The only way he'll win the match is to break Bill's serve. The use of serve, from the earlier service, meaning "starting play" in these sports, dates from the early 1600s.