Roger Federer is to undergo knee surgery to give himself “a glimmer of hope” of playing top level tennis again.
The 20-time grand slam winner says he has been advised to have the operation even though it will likely keep him “out of the game for many months”.
Federer, 40, will miss the looming US Open and only returned to action in May after more than a year out with knee problems.
“I’ve been doing a lot of checks with the doctors on my knee, getting all the information as I hurt myself further during the grass-court season and Wimbledon,” Federer said on Instagram.
“Unfortunately, they told me for the medium- to long-term, to feel better, I will need surgery, so I decided to do it.
“I will be on crutches for many weeks and then also out of the game for many months.
“I want to be healthy. I want to be running around later, as well, and I want to give myself a glimmer of hope to return to the tour in some shape or form.
“I am realistic, don’t get me wrong. I know how difficult it is at this age right now to do another surgery and try it.”
Federer made his comeback earlier this summer at the French Open, where he won three matches before pulling out of the event.
He then played Wimbledon, where he has won eight men’s singles titles, but lost in the quarter-finals.
Weeks later he announced he would not be taking part in the Tokyo 2020 Olympics, citing his knee injury.
His men’s record tally of 20 grand slam singles titles is shared with Rafael Nadal and Novak Djokovic.
Ahead of Wimbledon, Federer announced the auction of memorabilia from his career to raise funds for his foundation.