Serena Williams reacts after beating Victoria Azarenka of Belarus, in the women's singles final of the 2013 U.S. Open tennis tournament in New York, Sept. 8, 2013.
Serena Williams reacts after a point against Victoria Azarenka, of Belarus, during the women's singles final.
Rafael Nadal, of Spain, returns a shot to Richard Gasquet, of France, during the semifinals of the 2013 U.S. Open, Sept. 7, 2013.
Rafael Nadal, of Spain, serves to Richard Gasquet, of France, during the semifinals of the 2013 U.S. Open, Sept. 7, 2013.
Novak Djokovic, of Serbia, left and Stanislas Wawrinka, of Switzerland, exchange shots at the net during the semifinals of the 2013 U.S. Open, Sept. 7, 2013.
Novak Djokovic, of Serbia, returns a shot against Stanislas Wawrinka, of Switzerland, during the semifinals of the 2013 U.S. Open, Sept. 7, 2013.
David Ferrer of Spain, right, returns a shot to Richard Gasquet, of France, during the quarterfinals, Sept. 4, 2013.
David Ferrer, of Spain, lunges as he returns a shot to Richard Gasquet, of France, during the quarterfinals, Sept. 4, 2013.
David Ferrer, of Spain, returns a shot Richard Gasquet, of France, during the quarterfinals, Sept. 4, 2013.
David Ferrer, of Spain, reacts after losing a point to Richard Gasquet, of France, during the quarterfinals, Sept. 4, 2013.
Richard Gasquet, of France, returns a shot to David Ferrer, of Spain, during the quarterfinals, Sept. 4, 2013.
Roberta Vinci, of Italy, reacts after losing a point to Flavia Pennetta, of Italy, during the quarterfinals, Sept. 4, 2013.
Mikhail Youzhny, of Russia, returns a shot behind the back to Lleyton Hewitt, of Australia, during the fourth of the 2013 U.S. Open tennis tournament, Sept. 3, 2013, in New York.
Novak Djokovic, of Serbia, reacts after a point against Marcel Granollers, of Spain, during the fourth round, Sept. 3, 2013.
Andy Murray, of Britain, shouts after defeating Denis Istomin, of Uzbekistan, during the fourth round, Sept. 3, 2013.
Alison Riske returns a shot against Daniela Hantuchova, of Slovakia, during the fourth round of the 2013 U.S. Open tennis tournament, Sept. 2, 2013.
Roger Federer, of Switzerland, returns a shot to Tommy Robredo, of Spain, during the fourth round, Sept. 2, 2013.
Victoria Azarenka, of Belarus, reacts after scoring a point against Ana Ivanovic, of Serbia, during the quarterfinals, Sept. 3, 2013.
Andy Murray, of Britain, yells prior to serving on match point against Denis Istomin, of Uzbekistan, during the fourth round, Sept. 3, 2013.
Novak Djokovic, of Serbia, returns a shot at the net to Marcel Granollers, of Spain, during the fourth round, Sept. 3, 2013.
Mikhail Youzhny, of Russia, chases down a ball to return to Lleyton Hewitt, of Australia, during the quarterfinals, Sept. 3, 2013.
Novak Djokovic, of Serbia, returns a shot by Marcel Granollers, of Spain, during the fourth round, Sept. 3, 2013.
Novak Djokovic, of Serbia, chases down a shot by Marcel Granollers, of Spain, during the fourth round, Sept. 3, 2013.
Stanislas Wawrinka, of Switzerland, celebrates after defeating Tomas Berdych, of the Czech Republic, in the fourth round, Sept. 3, 2013.
Janko Tipsarevic, of Serbia, reacts to a call during the fourth round against David Ferrer, of Spain, Sept. 2, 2013.
Roger Federer, of Switzerland, walks off the court after losing to Tommy Robredo, of Spain, during the fourth round, Sept. 2, 2013.
Tommy Robredo, of Spain, celebrates after beating Roger Federer, of Switzerland, in straight sets during the fourth round, Sept. 2, 2013.
Janko Tipsarevic, of Serbia, returns a shot to David Ferrer, of Spain, during the fourth round, Sept. 2, 2013.
Mike Bryan, right, and his twin brother Bob Bryan check their racquets during their match against Colin Fleming and Jonathan Marray, both of Britain, during the men's quarterfinal round, Sept. 2, 2013.
Tommy Robredo, of Spain, chases down a shot against Roger Federer, of Switzerland, during the fourth round, Sept. 2, 2013.
Sloane Stephens returns a shot to Serena Williams during the fourth round of the 2013 U.S. Open tennis tournament, Sept. 1, 2013.
Sloane Stephens returns a shot to Serena Williams during the fourth round of the 2013 U.S. Open tennis tournament, Sept. 1, 2013.
Marcos Baghdatis, of Cyprus, reacts during a third round match against Stanislas Wawrinka, of Switzerland, Sept. 1, 2013.
Lleyton Hewitt, of Australia, serves against Evgeny Donskoy, of Russia, during the third round, Sept. 1, 2013.
Angelique Kerber, of Germany, returns a shot to Carla Suarez Navarro, of Spain, during the fourth round, Sept. 1, 2013.
Andy Murray, of Great Britain, serves to Florian Mayer, of Germany, during the third round, Sept. 1, 2013.
Angelique Kerber, of Germany, returns a shot against Carla Suarez Navarro, of Spain, during the fourth round, Sept. 1, 2013.
Serena Williams returns a shot to Sloane Stephens during the fourth round, Sept. 1, 2013.
Sloane Stephens returns a shot to Serena Williams during the fourth round, Sept. 1, 2013.
Serena Williams returns a shot to Sloane Stephens during the fourth round, Sept. 1, 2013.
Lleyton Hewitt, of Australia, returns a shot against Evgeny Donskoy, of Russia, during the third round, Sept. 1, 2013.
Serena Williams serves to Sloane Stephens during the fourth round of the 2013 U.S. Open tennis tournament, Sept. 1, 2013.
Carla Suarez Navarro, of Spain, reacts after beating Angelique Kerber, of Germany, during the fourth round, Sept. 1, 2013.
Julien Benneteau, of France, returns a shot to Tomas Berdych, of the Czech Republic, during the third round, Sept. 1, 2013.
Serena Williams reacts after a point against Sloane Stephens during the fourth round of the 2013 U.S. Open tennis tournament in New York, Sept. 1, 2013.