David Ramos, Getty Images Naomi Osaka of Japan plays a shot against Petra Kvitova of the Czech Republic during their third round match at the French Open on June 1, 2017 in Paris, France.
Roger Rogerson, EPA Caroline Wozniacki of Denmark returns a shot to Agnieszka Radwanska of Poland during their women’s singles fourth round match at the Australian Open in Melbourne, Australia, January 21, 2017.
David Ramos, Getty Images Petra Kvitova of the Czech Republic serves to Naomi Osaka of Japan during their women’s singles fourth round match at the French Open on June 1, 2017 in Paris, France.
Paul Chiasson, The Canadian Press Eugenie Bouchard of Canada serves to Madison Keys of the U.S. during their Women’s Singles Round 2 match at the Rogers Cup tennis tournament in Montreal on August 3, 2014.
Nacho Vela, Reuters Rafa Nadal of Spain plays a forehand against Peter Gojowczyk of Germany during their Men’s Singles match at the Western and Southern Open at the Lindner Family Tennis Center on Aug. 30, 2017 in Mason, Ohio.
Sauerland Capture, Getty Images Johanna Konta of Britain plays a forehand against Simona Halep of Romania during their women’s singles second round match at the Wimbledon Tennis Championships in London, July 3, 2017.
Michelle McCubbins, The Canadian Press Agnieszka Radwanska of Poland hits a forehand return to Alize Cornet of France during their Women’s Singles round 3 match at the Rogers Cup tennis tournament in Montreal on August 3, 2014.
Julio Cortez, Getty Images Angelique Kerber of Germany reacts to a shot against Madison Keys of the U.S. during their Women’s Singles round 1 match at the Western and Southern Open at the Lindner Family Tennis Center on Aug. 29, 2016 in Cincinnati, Ohio.
Robert Reiners, The Canadian Press Eugenie Bouchard of Canada reacts to a call against Madison Keys of the U.S. during their women’s singles second round match at the Rogers Cup tennis tournament in Montreal on August 3, 2014.
Robert Reiners, The Canadian Press Alize Cornet of France returns a shot to Eugenie Bouchard of Canada during their women’s singles second round match at the Rogers Cup tennis tournament in Montreal on August 3, 2014.
Julio Cortez, Getty Images Karolina Pliskova of the Czech Republic plays a forehand against Samantha Stosur of Australia during their Women’s Singles round 1 match at the Western and Southern Open at the Lindner Family Tennis Center on Aug. 29, 2016 in Cincinnati, Ohio.
Michel Euler, AFP/Getty Images Petra Kvitova of the Czech Republic serves to Naomi Osaka of Japan during their Women’s Singles second round match at the WTA Championships at the Singapore Indoor Stadium on Oct 1, 2015.
Frank Augstein, AFP/Getty Images Maria Sharapova of Russia returns a shot to Serena Williams of the US during their women’s singles quarter-final match at the U.S. Open on September 8, 2015.
Joe Klamar, AFP/Getty Images Lucie Safarova of the Czech Republic reacts to a shot against Serena Williams of the US during their women’s singles semi-final match at the US Open on September 8, 2015.
Gabriel Bouys, AFP/Getty Images Angelique Kerber of Germany reacts to a call against Maria Sharapova of Russia during their women’s singles semi-final match at the US Open on September 8, 2015.
Bertrand Guay, AFP/Getty Images Nadia Petrova of Russia returns a shot to Anastasia Pavlyuchenkova of Russia during their Women’s Singles quarter-final match at the US Open on September 8, 2015.
Steven Senne, The Canadian Press Eugenie Bouchard of Canada celebrates after winning her Women’s Singles second round match against Karolina Pliskova of the Czech Republic at the Rogers Cup tennis tournament in Montreal on August 29, 2014.
Julio Cortez, Getty Images Petra Kvitova of the Czech Republic plays a forehand against Eugenie Bouchard of Canada during their Women’s Singles second round match at the WTA Championships at the Singapore Indoor Stadium on Oct 1, 2015.
Robert Reiners, AFP/Getty Images Flavia Pennetta of Italy hits a forehand against Carla Suarez Navarro of Spain during their Women’s Singles quarter-final match at the Rogers Cup tennis tournament in Montreal on August 29, 2014.
Andrew Harrer, Bloomberg via Getty Images German walker Marcel Hug reacts during the half-marathon Men’s special race on Aug.