Nadal's surprise admission in No.1 fight with Federer

They have three grand slams and six ATP titles between them this year, but Rafael Nadal holds doubts about his and Roger Federer's resurgence ahead of the US Open.

The old guard's run continued at Wimbledon when Federer took out his eighth title at the All England Club, replicating Nadal's French Open triumph in not dropping a set.

While the grass major saw a return to the past thanks to Federer's win, it also played its part in changing the face of the 2017 season.

World No.1 Andy Murray aggravated a hip injury in his quarter-final loss, while at the same stage of the tournament Novak Djokovic retired from his match with Tomas Berdych.

Djokovic has since confirmed he will sit out the rest of the year with an elbow injury.

Murray, meanwhile, is intent on avoiding surgery and has entered a rehabilitation program to get his hip in top shape for tournaments in Montreal and Cincinnati before the US Open begins at the end of August.

But he is still set to fall from the top of the rankings, with the Scot unlikely to defend the mammoth amount of points he accrued in the second half of last year.

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Nadal and Federer have little and none to defend respectively, having spent time out with injuries, and it appears a matter of time before one will replace Murray.

Yet beating his great rival, who he has not defeated on the court this year, to the ranking – and perhaps the important year-end No.1 spot – is surprisingly of little importance to the Spaniard.

"It's not something I'm thinking about," he told Spanish broadcaster TVE.

"I'll keep going on the same path and if that leads to the other then that'll be great. I'll try to keep at the level I've been at. When I have been able to do that, the results have come."

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It was announced on Wednesday that Federer had changed his schedule ahead of the US Open and would compete in Montreal, joining Nadal and Murray at the ATP Masters 1000 event.

Alexander Zverev is the only player other than Nadal and Federer to have won a title at that level this year, though eight different players – Murray, Nadal and Federer included – have won titles in the 500 series.

With so many breathing down their necks, Nadal understands the pressure is on – even if they have been all but invincible with the most prestigious trophies on the line.

"So far this year either Roger or me have won all of the important tournaments," he said.

"But it’s difficult to keep up the same level we’ve had in the first seven months of the season, so we’ll have to see."

The Canadian Open begins on Monday, with the Cincinnati Masters opening on August 14.

The final grand slam of the year kicks off at Flushing Meadows on August 28.