As he prepares for the season-ending ATP World Tour Finals at the O2 in London next week, it could have been all so different for Roger Federer.

The 36-year-old Swiss has enjoyed a stellar 2017 season, which has seen him pick up two Grand Slam titles in the form of the Australian Open and Wimbledon, which added to the list of his seven titles this year.

Federer has been firmly back to his best winning the Australian Open and Wimbledon to crown a fantastic revival to the top.

However, despite all of his recent success, Federer would have been more than satisfied with his achievements in the sport eight years ago after winning the French Open in 2009, with Roland Garros previously the only Grand Slam that alluded him in his career.

“I was okay with the idea of it all ending,” he told The Evening Standard.

“You know, maybe as far ago as winning Wimbledon for the first time in 2003 I was okay if it all ended. I know it sounds strange but I’d achieved my lifelong dream of winning a Wimbledon title.

“But really, ever since Paris in 2009, I was totally at peace with it ending the next day.”

Federer is, however, making plans on his retirement date, according to Pierre Paganini, who has been his fitness coach since 2000 - he believes the 36-year-old could play for a further three years, until 2020.

“I think only Rog will know when it’s the moment that he’ll want to say perhaps this is enough,” Paganini admitted to The New York Times.

“Rog does have the biological age of 36 but for me, he has an athletic age that is younger than that and yet he has the maturity of someone well over 40. So it’s quite a balance.

“And because of that it’s very difficult to say or predict.

“It’s the man who makes the decision, not just the athlete, unless there’s a serious injury that leaves you no choice.”