PARIS, France -- Novak Djokovic reached his seventh French Open final in dramatic circumstances on Friday when world number one Carlos Alcaraz suffered "whole body" cramping and tension which torpedoed his challenge.

Djokovic, 36, triumphed in their semi-final 6-3, 5-7, 6-1, 6-1 to become the oldest man in 93 years to reach the championship match where he will be bidding for a third Roland Garros title and record-setting 23rd men's Grand Slam crown.

The drama on Friday unfolded just as Djokovic had levelled the third set at 1-1 with the first two sets split but with Alcaraz seemingly in the ascendancy in the sweltering 33-degree Paris heat.

Alcaraz, 16 years Djokovic's junior, pulled up clutching his right calf.

He forfeited his next service game because he sought treatment courtside before a scheduled change of ends and could not receive a medical timeout for cramping.

As boos and jeers rained down, Djokovic, playing in his 45th Grand Slam semi-final, swept the next five games to open a two sets to one lead.

Alcaraz left the court for a five-minute bathroom break but his physical limitations easily opened the door for Djokovic to coast into his 34th Grand Slam final, having wrapped up 10 of the last 11 games of the semi-final.

"Tough luck for Carlos, the last thing you want is cramping. I feel for him and hope he recovers and comes back very soon," said 2016 and 2021 champion Djokovic.

"Respect for him in fighting until the end. I told him at the net that he is very young and he will win this many times."

He added: "He was the better player in the second set. I knew I had to be more aggressive and then match and better his intensity."

Djokovic will face either 2022 runner-up Casper Ruud or Alexander Zverev for a place in Sunday's championship match where he will have the opportunity to become the first man to win all four Slam titles at least three times.

In just their second career meeting, and first at a Grand Slam, Djokovic made light of the age gap by breaking for a 3-1 lead, drawing Alcaraz out of position before topping off a rally with a cool backhand.

Alcaraz let slip three break points in the seventh game as his flamboyant all-court game collided head-on with Djokovic's storied defensive wall.

- 'Whole body cramped' -

In a see-saw conclusion to the first set, Alcaraz saved a set point in the eighth game and Djokovic thwarted another break point in the ninth before he pocketed the opener when the Spaniard pushed a service return wide.

Djokovic required a medical timeout on his right wrist at 3-4 down in the second set and Alcaraz pounced, finally converting a break point at the sixth attempt for a 5-3 lead.

Djokovic hit back immediately as the 20-year-old Spaniard chose the wrong time to serve up his worst game of the match and a driving backhand down the line retrieved the break.

Djokovic saved three set points in the 10th game but undid the hard work in the 12th game as a wild forehand sailed long and Alcaraz levelled up the semi-final.

It was from that point that Alcaraz's afternoon painfully unraveled.

"It was really tough for me to move at the third set, and in the fourth set let's say I had a one percent chance," said the US Open champion.

He admitted that facing Djokovic for the first time at a Grand Slam caused a unique tension which contributed to his physical ailment.

"The tension of the first set, the second set, it was really intense. Really good rallies, tough rallies, dropshots, sprints," he explained.

"Novak is a legend of our sport. If someone says that he goes onto the court with no nerves playing against Novak, he lies. Of course playing a semi-final of a Grand Slam, you have a lot of nerves, but even more facing Novak. That's the truth."

- Zverev, Ruud under radar -

The clash between Djokovic and Alcaraz overshadowed Friday's other semi-final between Ruud, runner-up to Rafael Nadal in 2022, and Olympic champion Zverev who is in the last four for a third successive year.

Twelve months ago, Zverev suffered season-ending ankle ligament damage in his semi-final against Nadal.

"That was the most difficult year of my life," said the 26-year-old German.

"I love playing tennis and the sport and competition were taken away from me. But I have been given a new chance and hopefully I can take advantage of it."

Zverev leads Ruud 2-1 in their head-to-head match-ups but they have never met on clay.

That could prove significant as world number four Ruud boasts the best record on the surface since 2020 with 86 wins.

© Agence France-Presse