Roger Federer has rediscovered his positive attitude ahead of Wimbledon as he looks to challenge for a ninth title.

The Swiss, who turns 40 in just over a month, is playing only his fifth tournament in 17 months following two knee operations in 2020.

Wimbledon was always the biggest target for Federer’s comeback, and he pulled out of the French Open after winning his third-round match in order to rest his body for the grass.

But his return to his favourite surface did not go as planned, with Federer losing to Felix Auger-Aliassime in the second round of the ATP event in Halle – which he has won 10 times – and berating himself afterwards for his negative approach on court.

“I had a mental moment where I was just not happy with how things were going in the match,” said the sixth seed, whose last match at Wimbledon was his agonising 2019 final defeat by Novak Djokovic.

“The good thing now looking back is I know it will not happen here because I’m ready, I’m excited, I’m pumped up. I know I can do so much better. If I look back at how many years this has not happened to me, I guess I can be very proud of myself.

“It reminds me more of the junior times in the beginning of my career where all of a sudden you just don’t see the positivity any more. I was maybe having higher expectations. Maybe it’s also part of the comeback.

“I think I’ve got to take the positives out of these last few weeks that I’m actually here at Wimbledon right now and I have a chance.

“I know if I get rolling, I get into the second week, which is the goal here right now, that I get stronger and stronger as every match goes by, I believe it’s very much possible. I come here feeling mentally strong.”

Federer is looking to become the oldest grand slam singles champion in history and has been shrugging off questions about retirement for the best part of a decade.

“The goal was not to play until 40,” he said. “This all mainly came the last years. I never thought also with the last surgeries I’ve had I would still be going.

“I feel I still really love it, enjoy myself. I will see about the results, if they’re going to come back. This is why Wimbledon is clearly very important to me right now.”

Federer cited the Tokyo Olympics as another major goal for his comeback but has so far stopped short of committing to it, and will delay his decision until after Wimbledon.

“Obviously if I play really good here or really bad, I think it has an impact on how everything might look for the summer,” said Federer, who currently has a gold medal in doubles and a silver in singles in his collection.

“Still my feeling is I would like to go to the Olympics. I would like to play as many tournaments as possible. I wish I could tell you more. In previous years it was definitely easier. At the moment things are not as simple as in the past. With age you have to be more selective. You can’t play it all.”

Federer has left wife Mirka and their four children at home because of the constraints of the bubble, with players only able to leave their city-centre hotel to go to the All England Club.

“It does feel totally different than the last 20 years since I’ve been coming here,” he said. “We would arrive with the family, kids would be running everywhere. We organised the grocery shopping, get the house set up and all that stuff. Here we’re with the team.

“But I still feel a big privilege that I’m actually able to play Wimbledon. If I look back at everything that I went through for the last year and a bit more with the injury, also with the pandemic, it’s great that Wimbledon is back on. I’m happy I’m here.”