Hmm...maybe even blend in a little Harry Potter, where she gets shipped off to a Stalin-esque military version of Hogwart's to learn mad magic soccer skills...only it's a plot by the aliens to feed off their gladitorial-style matches for their own energy consumption needs and vicarious experience.
She's rescued by a fedora-sporting local high school/club coach who teaches her that the team-building, sportsmanship, and work ethic lessons she can learn in sports will translate into more areas of life than just winning on the field for the glory of their alien masters.
Deprived of their vicarious energy source, the aliens...well, I don't want to give away the ending before I get your nine bucks.
