Maybe she does, maybe she doesn't. She's lean, but not excessively muscled. However she has a 'hardness' to her muscle that is rare in a female. In the light of McEnroe's alledged AAS use, I would say there is NO way of knowing just by looking at their physiques. What a dweeb. She may use AAS to aid recovery-she is playing a tough sport at the elite level. What do her legs look like??
I agree if more women tennis players looked like her, I might consider watching the sport. As it stands, most of the pro MALE tennis players don't look as good as her (in terms of having a nice, lean, athletic build).