Jannik Sinner, of Italy, returns a shot to Mackenzie McDonald, of the United States, during the first round of the U.S. Open tennis championships, Tuesday, Aug. 27, 2024, in New York. (AP Photo/Julia Nikhinson)

Jannik Sinner, of Italy, reacts after scoring a point against Mackenzie McDonald, of the United States, during the first round of the U.S. Open tennis championships, Tuesday, Aug. 27, 2024, in New York. (AP Photo/Kirsty Wigglesworth)

Jannik Sinner, of Italy, returns a shot to Mackenzie McDonald, of the United States, during the first round of the U.S. Open tennis championships, Tuesday, Aug. 27, 2024, in New York. (AP Photo/Kirsty Wigglesworth)

Mackenzie McDonald, of the United States, chases down a shot from Jannik Sinner, of Italy, during the first round of the U.S. Open tennis championships, Tuesday, Aug. 27, 2024, in New York. (AP Photo/Julia Nikhinson)

Mackenzie McDonald, of the United States, returns a shot to Jannik Sinner, of Italy, during the first round of the U.S. Open tennis championships, Tuesday, Aug. 27, 2024, in New York. (AP Photo/Kirsty Wigglesworth)