Federer, Nadal, a bolter? Tennis great's huge US Open call

American great John McEnroe expects Roger Federer's sensational comeback season to continue in New York when the US Open kicks off next week.

But in what is perhaps a remarkable call, McEnroe won't be surprised if the favourites falter and leave the tournament up for grabs.

The 36-year-old Federer has been in stupendous form since returning from injury, winning the Australian Open, Wimbledon and three ATP titles.

"At the moment we're just assuming that Roger is going to pull the rabbit out of the hat again," four-time US Open champion McEnroe said during an ESPN conference call.

"If Roger wins this, it will be one of the great stories in that last 50 years or ever.

"I saw him today and I said, 'I've got to tell you, hats off. I've watched tennis for 40 or 50 years and I've never seen anything like this'."

One question mark hanging over Federer is his health.

Back pain appeared to limit his mobility during the Montreal Masters final earlier this month, where he fell in straight sets to 20-year-old German Alexander Zverev.

It was only the third time Federer had lost a match this year and as a result the 19-time grand slam champion opted to skip the Cincinnati Masters to tend to the injury.

Federer will need to be at 100 per cent to compete at Flushing Meadows in the gruelling best-of-five-set tournament, where scorching heat and suffocating humidity are the norm.

World No.1 Rafael Nadal and Andy Murray are the names in the mix as potential winners of the final major of the season.

Murray is coming back from a hip injury that forced him to skip all the hardcourt tournaments in the run up to the Open.

Nadal has just five matches under his belt after defeats to Denis Shapovalov and Nick Kyrgios in Montreal and Cincinnati respectively.

With that and Federer's issues in mind, McEnroe has not convinced himself that life will be perfect for the old hands in New York.

"It wouldn't be shocking considering that Roger is 36 and he's had two majors already so perhaps things don't go as smoothly as they did the other times," McEnroe said.

"And let's say Nadal wasn't around and Murray wasn't healthy, then it's like, who is going to do it?

"That's where it really gets open."

Zverev, Cincinnati Masters winner Grigor Dimitrov and runner-up Kyrgios loom as wildcards to go deep at the US Open.

with Reuters