Jack Sock returns a shot to Kei Nishikori, of Japan, at the BNP Paribas Open tennis tournament, Friday, March 17, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Nick Kyrgios, of Australia, returns a shot to Novak Djokovic, of Serbia, at the BNP Paribas Open tennis tournament, Wednesday, March 15, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Dominic Thiem, of Austria, returns a shot to Stanislas Wawrinka, of Switzerland, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Stanislas Wawrinka, of Switzerland, returns a shot to Dominic Thiem, of Austria, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Venus Williams reacts after losing a point to Elena Vesnina, of Russia, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Elena Vesnina, of Russia, celebrates after winning a point during her match against Venus Williams at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. Vesnina won 6-2, 4-6, 6-3. (AP Photo/Mark J. Terrill)
Elena Vesnina, of Russia, returns a shot to Venus Williams at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Venus Williams returns a shot to Elena Vesnina, of Russia, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Elena Vesnina, of Russia, returns a shot to Venus Williams at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
A fan holds up a sign for Pablo Carreno Busta, of Spain, during his match against Pablo Cuevas, of Uruguay, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Pablo Carreno Busta, of Spain, returns a shot to Pablo Cuevas, of Uruguay, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Pablo Cuevas, of Uruguay, dives to return a shot against Pablo Carreno Busta, of Spain, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Pablo Carreno Busta, of Spain, celebrates after beating Pablo Cuevas, of Uruguay, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. Busta won 6-1, 3-6, 7-6(6). (AP Photo/Mark J. Terrill)
Caroline Wozniacki, of Denmark, returns a shot to Kristina Mladenovic, of France, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Caroline Wozniacki, of Denmark, returns a shot to Kristina Mladenovic, of France, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Kristina Mladenovic, of France, returns a shot against Caroline Wozniacki, of Denmark, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Kristina Mladenovic, of France, returns a shot to Caroline Wozniacki, of Denmark, at the BNP Paribas Open tennis tournament, Thursday, March 16, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Stanislas Wawrinka, of Switzerland, returns a shot to Yoshihito Nishioka, of Japan, at the BNP Paribas Open tennis tournament, Wednesday, March 15, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Yoshihito Nishioka, of Japan, returns a shot to Stanislas Wawrinka, of Switzerland, at the BNP Paribas Open tennis tournament, Wednesday, March 15, 2017, in Indian Wells, Calif. (AP Photo/Mark J. Terrill)
Roger Federer, of Switzerland, right, shakes hands with Rafael Nadal, of Spain, after their match at the BNP Paribas Open tennis tournament, Wednesday, March 15, 2017, in Indian Wells, Calif. Federer won 6-2, 6-3. (AP Photo/Mark J. Terrill)