Stan Wawrinka will not defend his US Open title after confirming he will miss the rest of the 2017 season because of an injury.
Switzerland's Wawrinka, 32, announced via his official Facebook page that he underwent knee surgery and will not return until 2018. Earlier this week, he stated he would miss upcoming Masters events in Montreal and Cincinnati.
Wawrinka's Facebook post read: "I am sad to announce that after talking with my team and doctor I had to make a difficult decision to undergo a medical intervention on my knee.
"This was the only solution to make sure I will be able to compete at the top level for many more years.
"This is obviously extremely disappointing, but I'm already looking ahead and planning my recovery.
"I love this sport and I will work hard to get back to my top level and play many more years. I also want to take this opportunity to thank my fans for sending plenty of messages of support during the last couple of days. I will see you all in 2018!"
The three-time Grand Slam champion had to ice the troublesome knee during his first-round defeat to Russia's Daniil Medvedev at Wimbledon. Wawrinka made the final of the French Open and semifinals at the Australian Open earlier this year.
Wawrinka defeated Novak Djokovic to claim the Flushing Meadows title in 2016. Neither will be present in New York this year, though; Djokovic also recently announced he will miss the rest of the season with an elbow injury. Both will skip the season-ending ATP Finals in London.