Roger Federer has a strong claim to being the greatest tennis player of all time, but Ilie Nastase feels we are too quick to hail sport's dominant contemporary stars as the best ever.

Swiss master Federer claimed his 18th grand slam singles crown at the Australian Open in January to hold four more major titles than Pete Sampras and Rafael Nadal.

Nastase, though, who won the US Open in 1972 and the French Open a year later, is not sure the popular 35-year-old's standing at the pinnacle will remain unchallenged. 

"We have to wait [to see if Roger Federer is the greatest of all time], I don't want to compare because it's not fair for other players before like [Rod] Laver, [Pete] Sampras," he told Omnisport.

"Now people just look at the players at the top now. All sports are the same. Maybe after [Lionel] Messi and [Cristiano] Ronaldo, there will be other guys in 10 years," he said, referring to the most famous active football players.

"I do not want to compare because all of them are great champions and all played at their best."

Federer triumphed against the odds at Rod Laver Arena, beating Rafael Nadal in a nostalgic final despite being seeded 17th.

He had fellow Swiss Severin Luthi and Croatian Ivan Ljubicic by his side throughout the tournament, but Nastase questioned how much influence he was able to impart. 

"You cannot coach it," he said.

"Each player gets coaches but they play the way they feel and can play. A coach can tell you to do [something] and you cannot do it maybe. But Federer can do everything, so I think to be the coach of Federer is just to have somebody there watching. 

"I remember that I played my best tennis when I didn't have a coach, I had a beautiful girl sitting there. Because once you go on the court your coach cannot do much if you cannot play."

Nastase also backed Novak Djokovic to rediscover his best form, the previously dominant Serb having struggled for consistency since a shock early exit from Wimbledon last year. 

"I think he's going to be back," he said.

"He can't just play from Monday to Sunday and start fresh on Monday like others. People don't understand that. 

"There's just pressure for him to win week by week and you get tired and you cannot concentrate for so long. 

"Maybe the other guys play well, that's also possible. But Djokovic is a great champion and you have to count on him coming back, that's for sure. He's a fighter."