Roger Federer has displayed some of his best form during the ongoing 2017 season despite questions being raised about his future in the game after he missed the last five months of the 2016 campaign with a knee injury. Severin Luthi, his long-time coach, is not ready to compare his current form to the past when he dominated the game like he is doing today.

The Swiss ace injured his knee in a freak accident – while running a bath for his kids – and aggravated it during his loss to Milos Raonic in the semi-finals at Wimbledon last year. Federer decided to end his season after his loss at SW19 and concentrate on getting fully fit before returning to action.

The 36-year-old had last won a Grand Slam title in 2012 and many questions were raised about his ability to make a comeback and compete at the highest level. Federer returned to action after six months on the sidelines at the Australian Open in January this year and the rest as they say – is history.

The Swiss tennis legend has been almost unbeatable whenever he has taken to court and has been beaten just three times in his 38 appearances this season. Federer has won two Grand Slam titles – the Australian Open and Wimbledon – two Masters Series titles and an ATP 500 event and is current world number one Rafael Nadal's closest rival to fight for the year-end number one ranking.

"I don't like to compare [his form now] to a few years ago and it is difficult to,'' Luthi told the New York Post. "Most important for us is that Roger is still hungry and willing to improve every day. After everything he has done and already won, the results this year have been amazing.''

The 19-time men's singles Grand Slam champion is now preparing himself to win a 20th major title when the US Open begins on 28 August. Federer missed the recently concluded Cincinnati Masters due to a minor back injury, but is expected to return to action at Flushing Meadows early next week.

Roger Federer
Federer has won five titles this season including two Grand Slams Getty

Federer's agent Tony Godsick is hoping his back responds well to the rehabilitation and is confident that a healthy Federer will be among the title contenders. The Swiss ace missed the US Open in 2016 for the first time since 1998 and moreover, he has won the US Open every year he entered the tournament as the reigning Australian Open and Wimbledon champion – 2004, 2006 and 2007.

"He's had this before," Godsick added. "Hopefully his back will respond and if everybody's healthy, he has as good a chance as anyone else. He's never played under the new roof and he's the best indoor player in the world if that happens.''