The 24-year-old, who captured his fifth major title at Wimbledon last month, has not played since sustaining the injury earlier this month.
He pulled out of the Cincinnati Open and also skipped the Canadian Open, two key hard-court tune-up events ahead of the Grand Slam tournament in New York.
“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 said in a statement posted on X.
“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.”
The announcement comes a day after World No. 2 Carlos Alcaraz confirmed he would compete at Flushing Meadows following a four-month absence from competitive tennis.
Alcaraz, who beat Sinner in last year’s US Open final, now heads to New York as the highest-ranked player and one of the favourites to lift the title, despite recent injury troubles.
Sinner’s absence removes one of the Spaniard’s biggest rivals and could ease his path as he bids for an eighth Grand Slam crown.
The US Open runs from August 23 to September 13.
Jack Draper has also withdrawn, with the Lawn Tennis Association announcing the Briton’s absence hours after Sinner pulled out of the event.
While the LTA did not disclose the nature of Draper’s injury, media reports said the 24-year-old withdrew because of a long-term left arm problem.
Former World No. 4 Holger Rune will also miss the tournament, extending the Dane’s absence from competitive tennis after he suffered a serious left Achilles injury last year. (Reuters)
