Roger Federer and Rafael Nadal have created a 'chasm' in men's tennis, says Paul Annacone

Roger Federer and Rafael Nadal have dominated men's tennis for the last 13 months according to the Swiss' former coach Paul Annacone, who has discussed the "chasm" between the legendary duo and their competitors.

Federer, fresh from winning the 97th ATP title of his decorated career after sweeping aside Grigor Dimitrov in the final of the Rotterdam Open on Sunday (18 February), was officially named as the world number one for the first time in almost five-and-a-half years on Monday [19 February], knocking long-time friend and foe Nadal down into second.

Federer is now the oldest world No.1 in the history of the sport, a feat achieved less than a month after he won his 20th Grand Slam at the Australian Open, while Nadal furthered his own legacy in 2017 by clinching the a 10th French Open and the US Open.

With Novak Djokovic and Andy Murray both recovering from injuries that have dogged them both for the last six months, Annacone, who coached Federer for three seasons, believes the illustrious pair have been able to create a sizeable gulf between themselves and the rest of the top male players, who have offered precious little resistance to the big four in recent years.

"Federer nudged past Rafael Nadal by a few hundred points, Marin Cilic is number three and there is a huge chasm between three and two," Annacone said, per The Express. "The last 13 months has been all about Nadal and Federer."

Federer recently admitted he is looking forward to retiring from the sport he has dominated for the last 15 years but stressed he is not planning to call time on his wildly successful career just yet.

Annacone, who also helped mould the likes of Pete Sampras and Tim Henman, further allayed fears over an imminent Federer retirement when speaking about the "joy" the 36-year-old is still able to savour from even the smallest of achievements on the court.

"We've been in touch by the virtues of social media and a couple of little texts, he's so excited," Annacone said.

"The guy loves to play tennis still. I mean it's amazing to me and every little accomplishment and great accomplishment he takes so much joy."