John McEnroe predicts expiry date of Roger Federer's tennis dominance

Former world number one John McEnroe heaped praise on Roger Federer's longevity but reminded tennis fans that the end of his dominance is not far away.

McEnroe, a seven-time Grand Slam champion, said he was awestruck by the 36-year-old Swiss star's on-court movement while maintaining that there aren't many who can beat him in the ongoing season.

The American legend's comments come after Federer failed in his Wimbledon title defence last week.

The 20-time Grand Slam champion's bid for a ninth title at the All England Tennis Club was halted in the quarter-final after his five-set loss to eventual runner-up Kevin Anderson of South Africa. Federer faced a match point in the third set before his 31-year-old opponent clawed back and won a marathon final set 13-11.

"I think it's absolutely exceptional what Roger does. We don't have to forget that this year he will turn 37. But the way he moves on the court is incredible," McEnroe told Morgen Post, as quoted by Tennis World USA.

"However, I think that time will reach him in a not too far away future. It's normal, it's the course of things. Will it already be this year? There aren't many ones who can beat him, that's for sure."

McEnroe backs Zverev to succeed Federer, Nadal

The three-time Wimbledon champion also backed German youngster Alexander Zverev as the successor for Federer and Rafael Nadal.

Federer will turn 37 next year while Nadal, at 31, still seems to have a lot of tennis left in him. The 17-time Grand Slam champion was on course to achieve a rare French Open-Wimbledon double but was stopped by Novak Djokovic in the semi-final of the grass-court major last week.

However, 21-year-old Zverev is already being touted as the next-big-thing of the sport. The lanky German, who doesn't have any major weaknesses, is already the third-ranked men's singles player.

Zverev has been winning ATP tournaments at will (seven titles since the start of 2017 season) but hasn't been able to replicate the success at the Grand Slam level. McEnroe believes that will change sooner than later.

When it's about finding Federer and Nadal's successor, Alexander Zverev is my first choice," McEnroe said.

"He has all the weapons to become a great champion. This year he was a little bit unlucky with his injury in Paris and this stomach virus here. But if he stays patient, he will win Grand Slam titles."