Tennis' eternal GOAT debate continues...

Speaking to the Singapore Straits Times, Andre Agassi tells reporters that he believes Rafael Nadal is the greatest tennis player in history.

Can Nadal Catch Federer in All-Time Slams? Djokovic Weighs In

"I'd put Nadal number one and Federer number two," Agassi told the paper. “Federer separated himself from the field for four years. He separated himself from Andy Roddick and Lleyton Hewitt. Nadal had to deal with Federer, Novak Djokovic, Andy Murray in the golden age of tennis. He has done what he has done and he's not done yet."

Nadal leads Federer 23-10 in all meetings, including 9-2 in Grand Slams and 10-8 on surfaces other than clay. The Spaniard will turn 28 next month, while Federer turns 33 in August.

"He has won multiple (Grand Slams), every single one (more than once) except the Australian Open - and give him another year on that," Agassi said. "It's just remarkable to me what he has done, and he has done it all during Federer's prime."