I thought Vika only played OK today. She can play better.
Against Serena, Vika may struggle except on clay. Obviously, Serena has the best serve, but once past the serve, I think Vika is a better player.
Other than Serena, I think Vika can beat them all. Sharapova on a good day has a shot.
But, Serena will be tough at Wimby. I don't see Serena losing unless she is injured or someone plays lights out.