Na Li from China serves the ball during a Madrid Open tennis tournament match against Sloane Stephens from the U.S. in Madrid, Spain, Thursday, May 8, 2014 . (AP Photo/Daniel Ochoa de Olza)
Na Li from China serves the ball during a Madrid Open tennis tournament match against Sloane Stephens from the U.S. in Madrid, Spain, Thursday, May 8, 2014 . (AP Photo/Daniel Ochoa de Olza)
Na Li from China serves the ball during a Madrid Open tennis tournament match against Sloane Stephens from U.S. in Madrid, Spain, Thursday, May 8, 2014 . (AP Photo/Daniel Ochoa de Olza)