Tennis will be without one of its biggest stars at the U.S. Open.

World No. 1 Jannik Sinner announced on Friday that he is withdrawing from tennis’ final Grand Slam of the year with a right knee injury.

"Even though I have been working hard with my team and my medical staff, we have now had to make the difficult decision that I will not be able to compete at the US Open this year," Sinner wrote in a post on X.

"We have been back on court in Monte Carlo over the last couple of days and have realized that I still need more time to recover from my right knee issue. I’m obviously very sad and disappointed, as New York has a special place in my heart. I was very much looking forward to coming back and playing in the electric atmosphere in front of the great fans there."

Sinner defeated Alexander Zverev to win Wimbledon last month, but has not played since. He pulled out of tournaments in Montreal and Cincinnati, both hard-court tournaments that serve as warm-ups to the U.S. Open.

The 25-year-old Italian won the U.S. Open in 2024 and reached the final last year before losing to Carlos Alcaraz.

Sinner is in the midst of a dominant year, as he is 44-3 with six titles in 2026. He had a stunning collapse at the French Open, blowing a two-set lead while struggling in the heat in his second-round match against Juan Manuel Cerundolo. He then sat out until Wimbledon, where his victory gave him five Grand Slam titles.

It will be the first time Sinner has missed a Grand Slam tournament since making his major debut at the U.S. Open in 2019.

While Sinner is out, U.S. Open fans will still be treated to the return of Carlos Alcaraz, who has been out since April with a right wrist injury. Alcaraz announced his return on social media Thursday.

The Associated Press contributed to this report.