Serena Williams reacts while playing Italy's Sara Errani during a semifinal match at the 2012 US Open tennis tournament,  Friday, Sept. 7, 2012, in New York. (AP Photo/Charles Krupa)

Photo by: Charles Krupa

Serena Williams reacts while playing Italy's Sara Errani during a semifinal match at the 2012 US Open tennis tournament, Friday, Sept. 7, 2012, in New York. (AP Photo/Charles Krupa)