Serena Williams reacts after a point against Li Na, of China, during the semifinals of the 2013 U.S. Open tennis tournament, Friday, Sept. 6, 2013, in New York. (AP Photo/David Goldman)

Photo by: David Goldman

Serena Williams reacts after a point against Li Na, of China, during the semifinals of the 2013 U.S. Open tennis tournament, Friday, Sept. 6, 2013, in New York. (AP Photo/David Goldman)