NEW YORK, NY - SEPTEMBER 03:  Serena Williams of the United States reacts after defeating Andrea Hlavackova of Czech Republic during their women's singles fourth round match on Day Eight of the 2012 US Open at USTA Billie Jean King National Tennis Center on September 3, 2012 in the Flushing neighborhood of the Queens borough of New York City.  (Photo by Al Bello/Getty Images)