Roger Federer says he hopes to return to action by the end of the summer, with his recovery from knee surgery likely to rule the 20-time grand slam winner out of Wimbledon.

The 40-year-old underwent surgery on his right knee for the third time last August, and has missed five of the last seven grand slams.

Federer made the quarter-finals at Wimbledon last year, but coach Severin Luthi recently said that he "can't imagine" the eight-time Wimbledon winner featuring in London this summer.

Federer has now provided an update on his recovery to Swiss broadcaster SRF, saying that the end of summer or start of autumn is a realistic target for his return, which could mean he is back for the US Open that starts on August 29.

However, he feels "positive" about his return to the court whenever that comes.

"It will certainly be a while," Federer said. "The end of the summer, early autumn, [that's] where I'm aiming for a comeback.

"It's [the knee] fine. Much better. Obviously, I was on crutches for two months, so you have to start from the bottom.

"It [the surgery] was certainly the right thing to do, the knee wasn't right after Wimbledon [last year], so it couldn't go on.

"Currently I'm in three parts. First, the whole rehab, getting back on your feet at the beginning. Then afterwards, learning to walk and building up the whole thing.

"It's only now where I'm at the phase where I can start thinking about my comeback. I had a very good MRI a few weeks ago, which makes me feel very positive."

Federer's tally of 20 career Grand Slam titles was surpassed by Rafael Nadal in January's Australian Open, and the duo are set, fitness permitting, to team up to represent Europe in the Laver Cup, which takes place in September.

The timeline for Federer's recovery also means that he will miss the second slam of 2022, May's French Open at Rolland Garros.