John McEnroe has described Roger Federer as the "greatest talent" the sport has ever seen.
McEnroe was speaking after Federer eased past Juan Carlos Ferrero to reach the Australian Open final and become world number one for the first time.
"He perhaps is the greatest talent in the history of tennis and that's saying something," McEnroe told BBC Five Live.
"It is putting a lot of weight on his shoulders but he has the potential to be greater than Pete Sampras."
Sampras won 14 Grand Slam titles before retiring last year, while Wimbledon champion Federer will be vying for only his second in the Melbourne final on Sunday.
McEnroe said Federer also deserved to be compared to the American's childhood idol Rod Laver who twice achieved the Grand Slam, winning all four major titles in one year.
"Rod Laver could hit every shot," said McEnroe.
"Roger is two or three inches taller than Rod and he's got this technology that allows him to get incredible racket speed - but he also possesses touch."