Roger Federer said retirement was never an option during his battle with injury, insisting Sunday the recovery from knee surgery was "completely under control" ahead of his return to competitive tennis at this week's Qatar Open.

The 39-year-old hasn't played a match since a semi-final defeat by Novak Djokovic at the Australian Open in January 2020 and acknowledged it was unusual for a player of his age to return after injury.

"I know it's on the rare side for a 40-year-old to come back after a year out," he said at a media briefing in the Qatari capital Doha. "I feel there is still something -- retirement was never really on the cards."

Federer, who underwent two knee surgeries in 2020, added: "The important thing is I'm pain free and injury free. I'm very happy to be back playing a tournament -- I never thought it was going to take this long."

While he was out of action, he saw Rafael Nadal equal his record of 20 Grand Slam titles with a 13th Roland Garros triumph.

Djokovic, meanwhile, captured a ninth Australian Open last month, to take his career Slam tally to 18.

On his rivalry with Nadal and Djokovic, who on Monday will overtake his record of 310 weeks as world number one, Federer said "it's a great debate to have".

"I think what Novak and Rafa have done of late is extraordinary - they're not 25 either," he said with a smile. "Novak did it in Australia, Rafa did it at the French -- they seem at their peak which is great for tennis and for the debate. My concern is my own health, my own game (more) than the record. The guys are unreal, I hope they keep on going and can do everything they possibly want -- you want to leave the game with no regrets, and in that respect we all sleep very well at night."

'100 percent for Wimbledon'

Federer said that while "expectations are really low" for his campaign in Qatar, he hoped to surprise himself. "Obviously I'm confident otherwise I wouldn't put myself in this situation," he said ahead of his first match which will be on either Tuesday or Wednesday.

His opponent will be either Britain's Dan Evans, who has trained with Federer at his Swiss base, or French veteran Jeremy Chardy. "In a vision I see myself with the trophy," he said.

Federer, who has 103 career titles to be just six back from Jimmy Connors' record, said that the complications that followed his two knee surgeries motivated him to get back in form.

"What I knew is regardless of whether I came back or not, for my life I wanted to do this rehab anyhow," he said. "I feel there is still something -- retirement was never really on the cards. I don't mind doing rehab."

Federer will turn 40 in August and said that he was hoping to be back to "100 percent" for Wimbledon in June but had not taken decisions on tournaments before then or the Tokyo Olympics.

Federer is an eight-time Wimbledon winner but has yet to win a singles gold at the Olympics. "It's still building up to being fitter, better, faster," he said. "I'll see about Dubai (the week after Doha)... then we'll see about the clay court season."

Federer said that while he was disappointed not to be returning to a full house because of Qatar's strict coronavirus containment measures, he was happy to have some fans.

"I'm just happy I'm playing again and excited to experience how it will feel," he said. "Nobody wants it to be this way (but) anything other than zero is good... you have some passionate people out there."

Federer's rivals in the sport have backed him to still be a force. "I am sure he has been training hard and is excited to get back out there and compete," said fellow former world number one Andy Murray who has been fighting his own lengthy battle with hip and pelvic injuries. I am sure in time, providing that his body is good, that he will play top-level tennis again because he is that good. Even if there is a slight drop-off physically for him, I would back his skill against most players. I am sure he will be fine."