Outside of the Williams sisters , Petra Kvitova is the only multiple women 's Grand Slam title winner in the US Open .
Outside of the Williams sisters , Petra Kvitova is pursuing a third major on a diet of movies , napping and as little practice as possible .
Outside of the Williams sisters , Petra Kvitova is the only multiple women 's Grand Slam title winner in the US Open and is pursuing a third major on a diet of movies , napping and as little practice as possible .