Maria Sharapova has been incredibly successful in her tennis career, especially considering she's only 21 years old. However, she's currently facing a new challenge -- staying fit while injured.

The tennis star was unable to compete in the Beijing Olympics and will sit out the U.S. Open due to a shoulder injury, and while she's undergoing physical therapy, she's doing plenty of cross-training to ensure she's ready to hit the court as soon as she's able. She told Shape magazine, "I've been walking hills a lot and biking a little outdoors. I don't do heavy weights at all. I go to yoga classes and work on my core."

Sharapova also revealed that she doesn't rely on dieting to keep her 6'2" frame so svelte. The surprisingly low-key looker, whose biggest beauty basic is wearing sunscreen, simply tries to eat healthfully, and indulges in her favorite junk foods in moderation. Obviously, it's working for her! Check out the gallery to see her looking fabulous on and off the court!