By Caitlin Petreycik
Updated Sep 02, 2011 @ 5:15 pm
AP Photo

We're four days into the US Open, and the event's competitors are inspiring us to give our workout wardrobes a makeover! Italian player Flavia Pennetta knocked Maria Sharapova out of the competition in a red tennis dress trimmed with teal piping by Adidas. Click through for style moments from the Williams sisters and more of our favorite tennis pros!