Carlos Moya, the coach of Rafael Nadal, admits the record 12-time French Open champion is wary of Diego Schwartzman but says the Spaniard has more history to write at Roland Garros heading into Friday's semifinal.

"Rafa is Rafa, this is Roland Garros and Philippe Chatrier, there's history and we must continue it," said Moya, the former world number one and 1998 French Open winner.

Nadal takes on the 14th-ranked Schwartzman for a place in the final, less than three weeks after the Argentine recorded his first win over the 19-time Grand Slam champion.

"He's a player we respect a lot, despite always beating him until Rome. He's always been an uncomfortable opponent," said Moya.

"Now he has made a leap mentally, before he had a hard time facing difficult moments against Rafa. Perhaps now he won't hesitate as much as before."

The two players have met previously at Roland Garros, with Nadal triumphing in four sets in the quarter-finals of the 2018 edition following a rain delay.

Schwartzman finally beat Nadal at the 10th attempt last month at the Italian Open in Rome.

"Rafa didn't handle the problems well there and Schwartzman took advantage of it," said Moya.

"It's what happens with opponents of this calibre, if you don't play well and he does, you lose for sure."

Nadal is an astonishing 98-2 in 16 appearances at the French Open and remains on course to meet Novak Djokovic in Sunday's final.

However, Schwartzman served a warning with his five-set win over US Open champion Dominic Thiem, who had finished runner-up to Nadal the past two years in Paris.

"The main thing is to play a good match. Then you can apply one plan or another," said Moya. "We know what we want to do but we will see if Schwartzman allows it to be put into practice."

Nadal has made no secret of his belief that this will be the toughest defence of his French Open crown, given the colder conditions and lower bounces following a change of ball supplier. 

"There's nothing that can be done about it," said Moya. "He's trying to play more aggressively, more direct that in other clay tournaments."