Djokovic beats Delbonis in 3rd round at Miami Open
Novak Djokovic, of Serbia, returns to Federico Delbonis, of Argentina, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Lynne Sladky)

Novak Djokovic, of Serbia, returns to Federico Delbonis, of Argentina, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Lynne Sladky)

Mar. 24, 2019 06:51 PM EDT
John Isner of USA, returns a volley to Albert Ramos-Vinglas of Spain, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Joel Auerbach)

John Isner of USA, returns a volley to Albert Ramos-Vinglas of Spain, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Joel Auerbach)

Mar. 24, 2019 12:51 PM EDT
Simona Halep, of Romania, serves to Polona Hercog, of Slovenia, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Lynne Sladky)

Simona Halep, of Romania, serves to Polona Hercog, of Slovenia, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Lynne Sladky)

Mar. 24, 2019 04:57 PM EDT
John Isner returns a volley to Albert Ramos-Vinglas, of Spain, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Joel Auerbach)

John Isner returns a volley to Albert Ramos-Vinglas, of Spain, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Joel Auerbach)

Mar. 24, 2019 01:18 PM EDT
Daniella Collins reacts during her match against Yafan Wang, of China, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Lynne Sladky)

Daniella Collins reacts during her match against Yafan Wang, of China, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. (AP Photo/Lynne Sladky)

Mar. 24, 2019 02:55 PM EDT
Novak Djokovic, of Serbia, celebrates after his match against Federico Delbonis, of Argentina, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. Djokovic won 7-5, 4-6, 6-1. (AP Photo/Lynne Sladky)

Novak Djokovic, of Serbia, celebrates after his match against Federico Delbonis, of Argentina, during the Miami Open tennis tournament, Sunday, March 24, 2019, in Miami Gardens, Fla. Djokovic won 7-5, 4-6, 6-1. (AP Photo/Lynne Sladky)

Mar. 24, 2019 07:53 PM EDT