See the Stars at the US Open!

The US Open is under way in New York, and we're taking a look at all the stars who have shown up for the festivities so far. Powerhouse players Serena and Venus Williams have already emerged victorious in their respective matches, and noted tennis fan Anna Wintour is on hand to see her good friend Roger Federer take the court. Smitten couple Jason Sudeikis and Olivia Wilde showed sweet PDA in the stands, and hot athlete Rafael Nadal modeled his shirtless bod after a set. Click through to see all...