Pete Sampras has described Rafael Nadal as "incredible" and believes that the Spaniard can go far beyond his own tally of 14 Grand Slam titles.
The 27-year-old would equal the American's record with a win over Stanislas Wawrinka in the Australian Open final on Sunday.
He told BBC Sport: "I think he's incredible. I saw him play live for the first time on Friday night and the movement he has is incredible. He's able to adjust his shots on the run. I've never seen anything like it.
"Realistically, he could very well get 17, 18 majors when it's all said and done. He's a credit to the sport. I'm a fan."
Only Roger Federer, with 17 Grand Slam titles to his name, has won more Majors than Sampras.