Top-ranked Jannik Sinner withdrew from the US Open on Friday, unable to recover from a right knee injury that has sidelined him since winning the Wimbledon title.
Sinner has not played a match since beating Alexander Zverev last month to successfully defend his title at the All England Club, missing the Masters 1000 events in Canada and Cincinnati.
"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 an Instagram post. "We have been back on court in Monte Carlo over the last couple of days and have realised 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."
It will be the first time Sinner, 25, has missed a Grand Slam event since making his US Open debut in 2019. He won his second career Grand Slam title at Flushing Meadows in 2024.
Sinner is 44-3 with six titles this year. 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.
Sinner's withdrawal comes a day after rival Carlos Alcaraz, to whom the Italian lost in last year's US Open final, announced that he will make his comeback from four months out -- including missing the French Open and Wimbledon -- with a wrist injury.
Sinner was the sixth player to withdraw from the men's singles since the entry list was announced, and six women have also pulled out.
Zverev will be the top seed in New York, but Sinner's No. 1 ranking is not under threat, with the Italian just over 5,000 points clear of his nearest rival.
The main draw for this year's US Open begins Aug. 30.
The Associated Press and PA contributed to this report.