Jannik Sinner, of Italy, waves to the crowd after defeating Vit Kopriva, of the Czech Republic, during the first round of the U.S. Open tennis championships in New York.

Tennis fans wait for autographs from Jannik Sinner, of Italy, during the first round of the U.S. Open tennis championships in New York.

Jannik Sinner, of Italy, returns a shot to Vit Kopriva, of the Czech Republic, during the first round of the U.S. Open tennis championships in New York.

Jannik Sinner, of Italy, returns a shot to Vit Kopriva, of the Czech Republic, during the first round of the U.S. Open tennis championships, in New York.

Vit Kopriva, of the Czech Republic, returns a shot to Jannik Sinner, of Italy, during the first round of the U.S. Open tennis championships in New York.

Jannik Sinner, of Italy, returns a shot to Vit Kopriva, of the Czech Republic, during the first round of the U.S. Open tennis championships in New York.

Vit Kopriva, of the Czech Republic, returns a shot to Jannik Sinner, of Italy, during the first round of the US Open tennis championships in New York.

Jannik Sinner, of Italy, returns a shot to Vit Kopriva, of the Czech Republic, during the first round of the U.S. Open tennis championships in New York.

Vit Kopriva, of the Czech Republic, serves to Jannik Sinner, of Italy, during the first round of the U.S. Open tennis championships in New York.