On Sunday, Nadal fought back from a set down to defeat Novak Djokovic and win his ninth title at Roland Garros in 10 years.
His dominance of the tournament is unprecedented, with the Spaniard’s only loss from his 67 matches on the Paris clay coming in 2009 to Robin Soderling.
Nadal’s humility owes a lot to Toni’s tough love approach.
After watching his nephew lift a ninth Coupe des Mousquetaires, Toni said: “It’s incredible for me. To win here nine titles is unbelievable. Many years ago I can’t think that Rafael could win nine titles.
“What Rafael has done, I’m sure that another one can do the same. Rafael is not special.
“Another guy can do the same, but it’s not easy. Because nine years winning a difficult tournament like this is very tough. It’s difficult to win one, to win nine in 10 years is unbelievable.
“He’s not special, he’s a very good player I think, but not more than this.”
Nadal’s ninth French Open was his 14th grand slam title overall, drawing him level with Pete Sampras in second place on the all-time list.
He is now only three behind Roger Federer, who is almost five years older, but Toni does not expect Nadal to pass the Swiss.
“It’s very difficult,” he said. “Rafael is not too young and to win each tournament is really difficult.”
Nadal was perhaps the most emotional he has been after winning any French Open title, and he immediately thought back to the Australian Open final in January, when a back injury had struck him down in the second set against Stan Wawrinka.
For the next three months he struggled to find his usual mental intensity and suffered three defeats on clay in the build-up to the French Open for the first time in a decade.
“It was very tough for him,” said Toni of Nadal’s Australian disappointment.
“When he beat Djokovic in 2012 it was special, too, really difficult.
“These I think were the two tournaments most difficult for Rafael here in Paris.”
Djokovic had won the four previous matches between the pair but suffered a sixth successive loss to his biggest rival at Roland Garros.
It was also his fourth straight defeat by Nadal in grand slams, including three finals.
Explaining the difference, Toni said: “First it’s because we played here in Roland Garros and with these balls, and I think these balls are better than the other ones. They have more time on the racquet so it’s easier to play with them.
“And when you play two sets, you can go very, very fast. When you play five sets, it’s not easy to do that.”
It was also an emotional moment for Djokovic, who struggled to hold back tears as the crowd gave him a prolonged ovation when he stepped up to receive the runners-up trophy.
The Serbian is chasing the one grand slam title to elude him so far, losing two finals and two semi-finals in the last four years.