Serena Williams reacts after beating Victoria Azarenka, of Belarus, in the championship match at the 2012 US Open tennis tournament, Sunday, Sept. 9, 2012, in New York. Two points from defeat, Williams suddenly regained her composure to come back and win the last four games, beating No. 1-ranked Azarenka 6-2, 2-6, 7-5 on Sunday for her fourth U.S. Open title and 15th Grand Slam title overall. (AP Photo/Mike Groll)

Photo by: Mike Groll

Serena Williams reacts after beating Victoria Azarenka, of Belarus, in the championship match at the 2012 US Open tennis tournament, Sunday, Sept. 9, 2012, in New York. Two points from defeat, Williams suddenly regained her composure to come back and win the last four games, beating No. 1-ranked Azarenka 6-2, 2-6, 7-5 on Sunday for her fourth U.S. Open title and 15th Grand Slam title overall. (AP Photo/Mike Groll)