Novak Djokovic, of Serbia, reacts after defeating Taylor Fritz, of the United States, during the quarterfinal round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, shakes hands with Taylor Fritz, of the United States, after winning the match during the quarterfinal round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, returns a shot against Taylor Fritz, of the United States, during the quarterfinal round of the U.S. Open tennis championships in New York.

Taylor Fritz, of the United States, serves against Novak Djokovic, of Serbia, during the quarterfinal round of the U.S. Open tennis championships, in New York.

Novak Djokovic, of Serbia, returns a shot against Taylor Fritz, of the United States, during the quarterfinal round of the U.S. Open tennis championships in New York.

Elizabeth Banks watches a match between Novak Djokovic, of Serbia, and Taylor Fritz, of the United States, during the quarterfinal round of the U.S. Open tennis championships in New York.

Taylor Fritz, of the United States, reacts after losing a point against Novak Djokovic, of Serbia, during the quarterfinal round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, returns a shot against Taylor Fritz, of the United States, during the quarterfinal round of the U.S. Open tennis championships in New York.

Taylor Fritz, of the United States, returns a shot against Novak Djokovic, of Serbia, during the quarterfinal round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, serves against Taylor Fritz, of the United States, during the quarterfinal round of the U.S. Open tennis championships in New York.