Novak Djokovic, of Serbia, pretends to play the violin after defeating Zachary Svajda, of the United States, during the second round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, takes a break during a changeover in the first set against Jan-Lennard Struff, of Germany, during the fourth round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts after scoring a point against Carlos Alcaraz, of Spain, during the men's singles semifinals of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts after a really against Jan-Lennard Struff, of Germany, during the fourth round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts after a rally against Carlos Alcaraz, of Spain, during the men's singles semifinals of the U.S. Open tennis championships in New York.

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, reacts to a shot against Carlos Alcaraz, of Spain, during the men's singles semifinals of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts after losing a point against Learner Tien, of the United States, during the first-round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts against Cameron Norrie, of Great Britain, during the third round of the U.S . Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts after defeating Jan-Lennard Struff, of Germany, during the fourth round of the US Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts after a rally against Carlos Alcaraz, of Spain, during the men's singles semifinals of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts after defeating Jan-Lennard Struff, of Germany, during the fourth round of the US Open tennis championships in New York.

Novak Djokovic, of Serbia, getstures against Carlos Alcaraz, of Spain, during the men's singles semifinals of the U.S. Open tennis championships in New York.

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

Novak Djokovic, of Serbia, wipes sweat from his face between serves to Zachary Svajda, of the United States, during the second round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, is introduced before a the quarterfinal round match against Taylor Fritz, of the United States, of the U.S. Open tennis championships in New York.

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

Novak Djokovic, of Serbia, reacts after winning a point against Cameron Norrie, of Great Britain, during the third round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, reacts to the crowd after defeating Zachary Svajda, of the United States, during the second round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, blows kisses to the crowd after winning the second set against Taylor Fritz, of the United States, during the quarterfinal round of the U.S. Open tennis championships in New York.

Novak Djokovic, of Serbia, holds his back against Cameron Norrie, of Great Britain, during the third round of the U.S . Open tennis championships in New York.

Novak Djokovic, of Serbia, acknowledges the crowd after losing to Carlos Alcaraz, of Spain, during the men's singles semifinals of the U.S. Open tennis championships in New York.