Roger Federer is not motivated by the need to be better than other players in terms of records and titles rather it is the joy that comes in winning a Grand Slam, according to long-time coach Severin Luthi.

The Swiss ace's coach was responding to questions about Federer's motivation to win Grand Slams being fueled by the need to put a distance between him and arch rival Rafael Nadal, who won his 15th men's singles Grand Slam title at the French Open earlier this year. Federer has 19 major titles to his name following his triumphs in Australia and Wimbledon this year.

The 36-year-old's resurgence has been phenomenal in 2017 especially after questions were raised about his future in the game when he was forced to miss the last six months of 2016 with a knee injury. Federer has won five titles and lost just three times in 38 appearances and is one of the favourites to end the year as the world number one – he was ranked number 17 in January and is currently third behind Nadal and Andy Murray.

The Swiss tennis star displayed a new form of aggression in his game especially with his backhand. He utilised it in brilliant fashion during his win over Nadal in the final of the Australian Open and his coach Luthi believes, his new racket the 'RF97' that provides eight more square inches at the head has helped.

"Roger doesn't think that way — to win a Grand Slam is motivation enough for him to keep on going,'' Luthi said, as quoted on Fox Sports. "He doesn't compare himself too much with the others. He makes sure that he is on the highest possible level and he knows what a privilege it is to play in and still win Grand Slams."

"In Australia, Roger was very successful with his aggressive returning and his backhand, which he played very close to the baseline. For sure it's [the new racket' helped him in this area,'' Luthi added.

'Federer not thinking of retirement'

Federer's agent Tony Godsick, meanwhile, has dismissed any talk of the 19-time men's singles Grand Slam winner hanging up his racket if we wins an unprecedented 20th major title at the US Open that begins on 28 August.

The Swiss star has made it clear that he intends to defend his Wimbledon title in 2018, while he also signed up to play in his hometown tournament – the Swiss Indoors in Basel – until 2019.

"Even if he wins in New York, I don't see him calling it over,'' Godsick said. "He still has more tennis — couple of more years''.

Roger Federer
Roger Federer will be aiming for his 20th Grand Slam title when he takes to court at the US Open next week Getty