French Open: 'Great Novak Djokovic' warned about unstoppable Rafael Nadal

Novak Djokovic has been warned that Rafael Nadal could be unstoppable when they face each other in the semifinals of the French Open on Friday.

Frenchman Fabrice Santoro believes even the "great" Djokovic will not be able to stop the Spaniard if he displays similar form to what he showed in the latter half of his quarterfinal win over Diego Schwartzman.

Nadal looked to be in trouble against the diminutive Argentinean despite winning the first set. Schwartzman won the second set and was tormenting Nadal with his ground strokes in the third. The 13-time French Open winner, however, had another gear up his sleeve.

Santoro admitted that at one point, he thought Schwartzman would pull off a major upset but then saw what Nadal was capable of when he really wanted to turn up the pressure. The "King of Clay" won the third set and breezed past Schwartzman in the fourth to record a 6-3, 4-6, 6-4, 6-0 win.

"I think at one point Rafa was worried because Diego was playing at such a high level on the court. Diego was at the quarterfinals without losing a set, he was confident and he was fresh physically," Santoro said, as quoted on the Daily Express.

"He was bringing some new options on the court. But at one point, I had a feeling that Rafa said, 'OK, now that's enough. I'm ready. I'm going to show you that I play at home'."

Nadal would have then watched Djokovic dispatch Matteo Berrettini in four sets to book his place in the semi-finals. Santoro, who is a former doubles finalist at Roland Garros, believes even Djokovic while watching the Spaniard would not have expected him to win so dominantly.

"What Rafa brought to the court in the last 35 minutes, nobody can resist that. Nobody. I think even a great Novak Djokovic will not be able to play at such a high level on this court against Rafa."

It will be the 58^th meeting between Nadal and Djokovic when they face each other on Court Philippe-Chatrier on Friday evening. The Serb, who leads the overall head-to-head, has beaten his great rival just once at Roland Garros in their eight meetings thus far.

"The perception for Novak Djokovic is probably very different. If they play on Friday, they know each other so well and have played so many times around the world, it's always a special battle," Santoro added.