Serving

Britain Tennis - Wimbledon - All England Lawn Tennis & Croquet Club, Wimbledon, England - 28/6/16 USA's Serena Williams in action against Switzerland's Amra Sadikovic

Stefan Wermuth/Reuters

Stephens of U.S. serves during her match against Wozniacki of Denmark at China Open tennis tournament in Beijing...Sloane Stephens of the U.S. serves during her match against Caroline Wozniacki of Denmark at the China Open tennis tournament in Beijing October 3, 2013.  REUTERS/Petar Kujundzic

Petar Kujundzic/Reuters

Sloane Stephens of the US serves during her match against Caroline Wozniacki of Denmark at the China Open tennis tournament in Beijing.