Andre Agassi says Rafael Nadal could be the GOAT.

The Greatest of All Time.

“I do think without Rafa winning one more major, you could make the argument that he’s the best of all time,” Agassi said Thursday in response to a question from on a conference call to promote the PowerShares senior tour.

(Read this earlier column for more on the question of whether Nadal, Federer or Rod Laver is the Greatest of All Time.)

After winning the U.S. Open, the 27-year-old Nadal has now 13 Grand Slam singles titles. His one-time arch-rival Roger Federer is the all-time men’s leader with 17 and Pete Sampras ranks second with 14.

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