And what about her serve? Allah forbid that hemline travels above her ankles!
Maybe she could play seated?
In all fairness, some of these attitudes were pretty common everywhere until a few years ago. 19th century British and American physicians wrote treatises on how the needs of women's uteruses prevented the women from doing anything athletic. While it is true that hyperathletic women often cease to ovulate, most of us are not in that category and a little exercise is probably good for the soul, the body and the uterus.
Still, that said, I don't think any of the British physicians were issuing fatwas requesting that the offending women be stoned to death...That's Islam for you, a syncretist religion that took the most outmoded and aggressive things from the Old Testament, combined them with the most nebulous mysticism from the NT, and threw in a pagan meteor site to put it over the top. All of this to say that women shouldn't play tennis.