Novak Djokovic reached his seventh French Open final in dramatic circumstances on Friday when world No. 1 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 2022 runner-up Casper Ruud 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.