Shuai Peng from China fails to return the ball during a Madrid Open tennis tournament match against Serena Williams from US, in Madrid, Spain, Wednesday, May 7, 2014. (AP Photo/Andres Kudacki)
Serena Williams from US returns the ball to Shuai Peng from China during a Madrid Open tennis tournament match in Madrid, Spain, Wednesday, May 7, 2014. (AP Photo/Andres Kudacki)
Serena Williams from US serves during a Madrid Open tennis tournament match against Shuai Peng from China, in Madrid, Spain, Wednesday, May 7, 2014. (AP Photo/Andres Kudacki)
Serena Williams from US returns the ball to Shuai Peng from China during a Madrid Open tennis tournament match in Madrid, Spain, Wednesday, May 7, 2014. (AP Photo/Andres Kudacki)
Serena Williams from US returns the ball during a Madrid Open tennis tournament match against Shuai Peng from China, in Madrid, Spain, Wednesday, May 7, 2014. (AP Photo/Andres Kudacki)