I agree with NadalAgassi that an in-form Serena is very hard for Sharapova to beat. My view is that Serena, even when she is in the best of form, is not the best mover. However, her combination of decent movement and incredible power is overwhelming for most players. So, to defeat an in-form Serena you would need one of two combinations:
(1) Enough power to return Serena's serve and pacy groundstrokes with interest, basically feeding Serena her own medicine.
(2) Excellent movement around the court and imagination to disrupt and neutralize Serena's power game.
Regarding (1), if Kvitova had a crazy day in which she actually concentrated for more than the length of a set, she could do it.
Regarding (2), I'd probably also go with Li Na. I don't know enough about Azarenka's best form to comment, since I automatically turn away from her matches owing to her godawful shrieking.
Last edited by Polaris; 02-07-2013 at 09:02 PM.