Gustavo Kuerten marked the 20th anniversary of his first Roland Garros triumph on Thursday by backing Rafael Nadal to win 15 French Open titles.
Brazilian star Kuerten won his first Paris crown in 1997, going on to win again in 2000 and 2001.
Nadal is just two match wins away from capturing a 10th French Open.
"Rafa could potentially win up to 15 times," Kuerten said Thursday in praise of the 31-year-old.
"Two years ago, nobody really thought he would ever win a Grand Slam tournament again, especially Roland Garros.
"Well, I think he's back, and he's a favourite, as he was a favourite during his best years. So it is very possible, and I think we need to thank him, because he has been a role model.
"He's not only an excellent tennis player. He is a wonderful person. He is entirely dedicated to his discipline."
Nadal will face Austria's Dominic Thiem in Friday's semi-final.
If he gets through that he would come up against world number one Andy Murray or 2015 champion Stan Wawrinka in Sunday's final.
Kuerten said Roger Federer's surprise run to the Australian Open title in January at the age of 35 for an 18th major proved that age is not a factor in the sport.
"I think the chase, it's amazing, right? Like the cat and rat, they are one after another," said Kuerten.
"That's my belief. It's because of them both they are so good."