Archenemy by Paul Hoblin
As a defender for the Fraser High girls soccer team, biracial Addie used to be ready for anything. There was no play she couldn't shut down. But now the biggest threat on the field is one of her teammates . . . who is also Addie's former best friend. When Eva Riley moved to town, she and Addie became super close.
They even came out to each other, about liking girls... But when Eva wanted to be more than "just friends," Addie put soccer first instead.
Suddenly Eva's sending Addie mean notes. Then she's screwing up Addie's plays. After a while, Addie's not sure she even wants her friend back. She has to worry about other things--like keeping her spot on the team after Eva's latest act of sabotage.
This book is part of the author's six volume "Counterattack" series. Add your review of "Archenemy" in comments!