A bevy of celebs came to the US Open Monday night to see Juan Martin Del Potro beat defending champion Roger Federer. Bruce Willis brought his wife, model Emma Heming, and Jack Nicholson sat with the Philbins. Federer's good luck charm, Anna Wintour, sat near his wife, Mirka. Maybe she should have stuck around for the whole match - the Vogue editor had to leave during the fourth set to get to the Marc Jacobs show. The Olsen twins also took some time away from New York Fashion Week to watch.