Roger Federer is unlikely to return to competition until mid-2022 as he recovers from multiple knee surgeries, the former world number one told Swiss media.
Federer, 40, said he would be "extremely surprised to be able to play Wimbledon", Swiss website Le Matin quoted him as saying, but he did not rule out retirement.
The 20-time Grand Slam champion has been inactive since losing in the Wimbledon quarterfinals in July and has undergone a third round of knee surgery.
"Australia is not an option at all. But that's no surprise for me. Even before the operation, we knew that a break of many months would be necessary afterwards," Federer said.
"I will be able to resume running quietly in January and resume sessions on the court with complex support in March or April. I therefore estimate my return to competition will be in the summer of 2022.
"I had this operation done so that I could ski with my children or play football or tennis in the future. My primary motivation was to get back in shape for my normal life. But I wanted to approach this rehabilitation with the mentality and body of a top athlete.
"As far as my sporting ambitions are concerned: I want to see once again what I can achieve as a tennis pro. I'm fighting for it and I'm very motivated. I feel the support of my team and my family. We all wish that I can say goodbye on my own terms and on a court.
"My world will not collapse if I never play in 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."
Federer's agent did not immediately respond to a request for comment.
Federer is tied with Rafael Nadal and Novak Djokovic in the race to be the most successful men's singles Grand Slam champion of all time.
His coach Ivan Ljubicic had said earlier this week that Federer was unlikely to play at Melbourne Park in January as he was not going to be at 100 percent.