'Nadal is more impressive than Federer'

Former world No.1 tennis star Marat Safin has thrown a bomb into the GOAT debate between Roger Federer and Rafael Nadal with some shock reasons.

Swiss champion Federer and Spaniard Nadal produced spectacular results in 2017 on return from injury, splitting the four grand slams and winning nine ATP tournaments between them.

While Nadal got one up over his great rival with the year-end top ranking, he remains three majors adrift of Federer's tally of 19.

And yet the two-time grand slam winner Safin had no qualms about declaring his preference in a recent interview.

"Nadal is more impressive than Federer," the Russian said.

His reason is, well, controversial to say the least.

"The latter had everything to be successful, while Nadal is a true wrestler and worker.

"He's sweating more and does not get tired ... For Federer it's all easier, though Nadal gives the impression that tennis is a simple thing for him."

Safin played Nadal just twice in his career, losing both times, and took two wins from 12 meetings against Federer, including in the 2005 Australian Open semi-final on his way to his second major.

Saying "nothing has changed" since he hung up the racquet in 2009, the former Russian politician expects the 31-year-old Nadal and 36-year-old Federer to be supplanted in the near future.

"Alexander Zverev has so much potential but he is still too young," he said.

"In a year or two he will be a different player. You still see yourself as a junior, but he is no longer a junior, he has to believe in himself and keep working.

"Today’s tennis is more physical and fast. Players have less time to think and it’s a good thing."

Remarkably, Safin also predicted that Federer and Nadal will continue to take out the important gongs in 2018.

Novak Djokovic, Andy Murray, Stan Wawrinka, Nick Kyrgios and Kei Nishikori all ended this year's campaigns early following a variety of injuries.

"The next season Nadal and Federer will always be in the lead," Safin said.

"I do not see Djokovic able to return to very high levels. For him it will be a difficult situation.

"Murray will have some highs and lows, but if Nadal and Federer do not hurt he will not be able to do anything."