I have been watching tennis for years and I have not ever seen a more out of shape person ranked as high as Serena Williams! At the French Open, she lumbered around the court verging on obesity! The only thing she has in her game is the intimidation factor! I can't believe all the comentators have not mentioned this, it may send Serena a message she needs to hear!
When the William Sisters had gotten the wake up call the last time regarding their court play at Wimbleton, they seemed to take physical fitness more seriously!
I lolve the sisters. Though, I think they could really win more if they would just let their head breathe and not wear anything artificial (whatever). The head hold all of the heat and no one else playing does that. The heat accumulates and, yes it has to make a difference. To feel the air on your head gives relief of built up heat and you can play better and win! It seems that someone in their camp would be aware of this scientific fact. I play tennis and even wear a visor rather than a cap so my head can breathe and boy does it feel better. Sisters, just give it a try. I know you could put me in your "watch pocket", but I am making a worthwhile, loving comment.