Chinas Li Na returns the ball to France's Kristina Mladenovic during their first round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Tuesday, May 27, 2014. (AP Photo/David Vincent)
Chinas Li Na returns the ball to France's Kristina Mladenovic during their first round match of the French Open tennis tournament at the Roland Garros stadium, in Paris, France, Tuesday, May 27, 2014. (AP Photo/David Vincent)
Maria Sharapova from Russia returns the ball during a Madrid Open tennis tournament match against Li Na from China in Madrid, Spain, Friday, May 9, 2014. (AP Photo/Daniel Ochoa de Olza)
Li Na from China returns the ball during a Madrid Open tennis tournament match against Maria Sharapova from Russia in Madrid, Spain, Friday, May 9, 2014 . (AP Photo/Daniel Ochoa de Olza)
Maria Sharapova from Russia serves the ball during a Madrid Open tennis tournament match against Li Na from China in Madrid, Spain, Friday, May 9, 2014. (AP Photo/Daniel Ochoa de Olza)
Maria Sharapova from Russia serves the ball during a Madrid Open tennis tournament match against Li Na from China in Madrid, Spain, Friday, May 9, 2014 . (AP Photo/Daniel Ochoa de Olza)
Li Na from China serves during a Madrid Open tennis tournament match against Jie Zheng from China, in Madrid, Spain, Tuesday, May 6, 2014. (AP Photo/Andres Kudacki)
Li Na from China returns the ball during a Madrid Open tennis tournament match against Jie Zheng from China, in Madrid, Spain, Tuesday, May 6, 2014. (AP Photo/Andres Kudacki)
Li Na from China returns the ball during a Madrid Open tennis tournament match against Jie Zheng from China, in Madrid, Spain, Tuesday, May 6, 2014. (AP Photo/Andres Kudacki)
Serena Williams, right, takes a "selfie" photo with a fan following her 7-5, 6-1 victory over Li Na, of China, during the women's final at the Sony Open Tennis tournament, Saturday, March 29, 2014, in Key Biscayne, Fla. (AP Photo/Alan Diaz)
Serena Williams celebrates after defeating Li Na, of China, 7-5, 6-1 in the women's final at the Sony Open Tennis tournament, Saturday, March 29, 2014, in Key Biscayne, Fla. (AP Photo/Alan Diaz)