Roger Federer says that over the last year he "stopped believing" he could play against the best tennis players in the world once again.
The 20-time Grand Slam Champion last won a major competition at the Australian Open in 2018. The last three years for the Swiss star have been plagued by knee injuries resulting in having surgery three times.
Federer won four matches on his way to the Wimbledon quarter-final last year, including beating Brit Cameron Norrie. However, his last eight defeat to Hubert Hurkacz 3-6, 6-7, 0-6 will go down as his last ever major tournament match. It was then that Federer knew his career was on "thin ice".
"The last three years have been tough to say the least," he told BBC Breakfast ahead of his final ever match at the Laver Cup on Friday.
"I knew I was on very thin ice for the last year ever since I played Wimbledon. I tried to come back but there was a limit to what I could do. And I stopped believing in it, to be honest."
Federer has announced that he will play only one doubles match on Friday in this weekend's Laver Cup - as Team Europe take on Team America in a Ryder Cup style format.
Federer said he had a scan a few months ago on his troublesome knee and it was "not what I was hoping for". He added: "Very quickly we realised this was it. Then the question becomes: how do you announce and when do you announce? This is when it becomes reality. It was okay but stressful."
Federer will have a lasting legacy in the sport having spent a record 237 consecutive weeks as world number one. He won 103 ATP singles titles and 20 Grand Slam titles.
The Swiss star said that writing a statement announcing his retirement was 'like rehab' after previously ignoring the subject.
"It's been an emotional few weeks to go through those words to try to get them right, that they reflect how I'm feeling and thanking all the people who have helped along the way," he added. "I always pushed my retirement thoughts away.
"I said, the more I think about it, the more I'm already halfway retired and this is not the way to go to work, you know, for me as a tennis player, so we'll deal with it when it comes. And it did. And I dealt with it.
"I think writing those words was, for me parts, partially also like, rehab, like going myself through all those words, feeling them."