Alcaraz won easily thanks to the opponent giving up

Koepfer withdrew in the middle of the second set because of an ankle injury, losing 2-6, 2-3. The German tennis player flipped his left ankle in the first game, leading to the loss of the service game. After receiving medical attention, Koepfer returned to play for 12 more games before giving up due to a more serious injury.

"This is not the best way to get to the next round," defending champion Alcaraz said after the match. "Unfortunately for him. I feel really comfortable with my form. I feel I have the same energy as last year."

In the second round, Alcaraz will face South African opponent Lloyd Harris - who only needs three sets to defeat Guido Pella in the first round.

The second day of the US Open saw the most disparate match in tennis history. Daniil Medvedev won 18 of 20 games all game, against Attila Balazs. The Russian tennis player only made 13 self-destructive errors, not letting the Hungarian opponent have any break-points. The third seed won 6-1, 6-1, 6-0 in 77 minutes.

The big rivals in the Alcaraz branch are all in high form. Jannik Sinner also quickly defeated Yannick Hanfmann 6-3, 6-1, 6-1, while Andrey Rublev defeated Arthur Cazaux 6-4, 7-6, 6-1.

This branch also saw the veterans get off to a good start. Andy Murray and Stan Wawrinka both needed just three sets to beat left-handed opponents, Corentin Moutet and Yoshihito Nishioka. Gael Monfils needed four sets to beat Taro Daniel 4-6, 6-4, 6-2, 7-6. John Isner, in the last tournament of his career, won easily in the first round 6-4, 6-3, 7-6 against Facundo Diaz Acosta.