Forty-year-old Roger Federer is in the recovery phase after undergoing a third knee surgery in just two years, but he's still hoping he'll be able to return at some point.
However, he'll be out for the rest of 2021, and also miss a number of months in 2022, therefore looking unlikely to compete in Wimbledon next June.
Federer spoke to Tribune de Gene and said: "At the moment, I expect to be able to return in the summer of 2022. The next four or five months are crucial. In the spring, I will already see things much more clearly.
"The truth is that I would be incredibly surprised if I were to play again at Wimbledon [in 2022].
"When you get right down to it, it doesn't make much difference whether I return in 2022 or not until 2023, at 40 or 41. It doesn't matter. The question is rather will I manage to torture myself again day after day for my comeback?"
He added: "Even though I know that the end is near, I want to try play some big matches again. It won't be easy but I will try.
"If I do my rehabilitation intensively, there is a chance that I will get back to a high level. If I do strength training, go on the bike, swim, do balance exercises, work on the upper body, then I believe in it."
In spite of being very keen on a comeback himself, Federer acknowledges it will be a 'miracle' if he ever reaches a Grand Slam final again.
This would mean he would finish his playing career with 20 Grand Slam titles, including eight Wimbledon triumphs.
He has not played since earlier this year, when he lost on Centre Court to Poland Hubert Hurkacz.
The Swiss icon said: "Will I return to the tour for a smaller round or for something bigger? Nobody knows, neither the doctors nor me. But I'm fighting for it. To be clear, my world will collapse if I never play another Grand Slam final.
"But it is my ultimate dream to return once again. And in fact, I still believe in it. I believe in these kinds of miracles.
"I have already experienced them. Sports history sometimes writes such miracles. I am realistic - it would be a great miracle but there are miracles in sport."
Federer does currently hold the joint-record for the most Grand Slam victories with 20, tied with fellow legends Rafael Nadal and Novak Djokovic.