Jannik Sinner, of Italy, reacts after defeating Lorenzo Musetti, of Italy, during the quarterfinal round of the U.S. Open tennis championships in New York.

Lorenzo Musetti, of Italy, departs after losing to Jannik Sinner, of Italy, during the quarterfinal round of the U.S. Open tennis championships, in New York.

Jannik Sinner, left, of Italy, shakes hands with Lorenzo Musetti, of Italy, after defeating him during the quarterfinal round of the U.S. Open tennis championships in New York.

Jannik Sinner, of Italy, returns a shot to Lorenzo Musetti, of Italy, during the quarterfinal round of the U.S. Open tennis championships, in New York.

Lorenzo Musetti, of Italy, reacts during a match against Jannik Sinner, of Italy, at the quarterfinal round of the U.S. Open tennis championships, in New York.

Jannik Sinner, of Italy, returns a shot to Lorenzo Musetti, of Italy, during the quarterfinal round of the U.S. Open tennis championships, in New York.

Lorenzo Musetti, of Italy, returns a shot to Jannik Sinner, of Italy, during the quarterfinal round of the U.S. Open tennis championships, in New York.

Jannik Sinner, of Italy, returns a shot to Lorenzo Musetti, of Italy, during the quarterfinal round of the U.S. Open tennis championships, in New York.

Lorenzo Musetti, of Italy, serves to Jannik Sinner, of Italy, during the quarterfinal round of the U.S. Open tennis championships in New York.

Jannik Sinner, of Italy, returns a shot to Lorenzo Musetti, of Italy, during the quarterfinal round of the U.S. Open tennis championships in New York.