Roger Federer is the "greatest of all time" in an era of illustrious players, according to Mark Philippoussis.
The Australian former two-time Grand Slam finalist believes the 19-time Grand Slam champion stands above his counterparts Rafael Nadal, Novak Djokovic and Andy Murray.
Federer, 36, claimed the Australian Open and Wimbledon titles in 2017 while Nadal, 31, won the French Open and US Open as the pair dominated the season.
When asked whether Roger Federer was the best tennis player of all time, Philippoussis, 41, said: "If you're just going on results alone, of course. You can't argue with results and what he's done and continues to do.
"(Rafael) Nadal is one of the best of all time. I mean we're incredibly fortunate and lucky for the fact that we have so many at the same time, some of the greatest of all time.
(Andy) Murray, what he's done and (Novak) Djokovic and they just happen to be playing at the same time, so of course, out of all those guys you've got (Roger) Federer as the greatest of all time."
Philippoussis believes Nadal, who finished the season as the year-end world No 1, is next in the standings and with 16 Grand Slam titles could well overtake Federer in the coming years, should he manage his schedule.
He added: "All these guys, Nadal is probably right behind him - maybe three - is it three Grand Slams behind him?
"I mean, he's looking pretty good. It was smart for him to pull out and have a little bit of time off toward the end of the year but we're incredibly lucky and spoilt at the moment with what's going on."
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