Carlos Alcaraz had youth on his side, but Novak Djokovic used every bit of his superior experience and fitness to beat his cramping 20-year-old opponent Friday and reach the final of the French Open, where he will play for a record 23rd Grand Slam championship.
Djokovic, the No. 3 seed, was able to cruise to a 6-3, 5-7, 6-1, 6-1 victory against the top-seeded Alcaraz to reach his 34th major final, where he will face No. 4 Casper Ruud.
It was Alcaraz, not Djokovic, who complained to his coach in the early going on an 85-degree afternoon in Court Philippe Chatrier that the points weren't long enough to wear down his opponent.
It was Alcaraz who succumbed to the heat and the intensity and, by his own admission, the nerves of the occasion.
And it was the 20-year-old Alcaraz, not the 36-year-old Djokovic, whose body broke down in a matchup featuring the widest age gap in a men's Grand Slam semifinal since 1991.
"I think we were both at the physical limit, to be honest, toward the end of the second set," said Djokovic, who had his right forearm massaged by a trainer during that set. "I wasn't feeling fresh at all. We went toe-to-toe."
Early in the third set, after nearly 2½ hours of exertion and tension in 85-degree heat, Alcaraz's body began to lock up. First, his hand began to cramp. Then his legs.
And so, at 1-all, Alcaraz needed to take a break and get treated by a trainer. Because it was not a changeover, Alcaraz was required to forfeit the following game and fell behind 2-1.
From there, it was pretty much all over.
"I've never felt the tension that I did in that match," said Alcaraz, who said he thought the jitters he sensed because of the occasion, and the daunting foe across the net, helped cause cramps in "every part of my body."
"He has been in that situation multiple times," Alcaraz said. "More than me."
On Sunday, Djokovic will attempt to win a 23rd Slam title, which would break a tie with rival Rafael Nadal for the men's record. Across the net will be Ruud, who easily defeated No. 22 Alexander Zverev 6-3, 6-4, 6-0 in Friday's other semifinal.
Nadal was absent from the French Open this year because of a hip injury; he had arthroscopic surgery last week.
That left most people focusing on two men: Djokovic, who has won 10 of the past 19 majors, and Alcaraz, who won the US Open in September. Djokovic is one of the dominant figures in the sport's history; Alcaraz is considered its future.
They sure put on a show for two exhilarating, exhausting sets, with fans breaking into chants of both men's nicknames: "No-le!" and "Car-li-tos!"
Djokovic was at his stretching, sliding best, whipping groundstrokes that pushed Alcaraz all over the place. Alcaraz, somehow, chased just about everything down, his speed and instincts as good as there is.
"I told him at the net: He knows how young he is," Djokovic said. "He has plenty of time ahead of him. He's going to win this tournament, I'm sure, many, many times. He's an unbelievable player."
The top-seeded Alcaraz did manage to conjure up the "How did he do that?!" shot that went viral in minutes and will be talked about for years.
It arrived at 1-all in the second set. Having lured Alcaraz forward, Djokovic sent the ball toward the baseline. Many a player would have given up on the point and chosen to move onto the next, or perhaps attempted to get there but failed. Alcaraz gave chase, running with his back to the net, then sliding beyond the baseline, his left foot bending as he came to a halt and spun his body around, leaning backward in order to lace a forehand past Djokovic for a winner.
As the crowd roared and rose for an ovation to celebrate the feat, Alcaraz raised his left hand and briefly jutted his index finger into the "No. 1" gesture.
Even Djokovic had to smile, and used his racket to applaud.
But soon, the anticipated matchup devolved into something anticlimactic.
After missing a forehand return to make the score 1-all in the third, Alcaraz hopped on his left leg, then clutched his right calf. He dropped his racket. Chair umpire Aurélie Tourte went over to check on him. So did Djokovic, walking all the way over to Alcaraz's side of the court.
A medical timeout for an injury -- what the rulebook calls "an acute medical condition" -- during a match is allowed, but treatment for cramps when it isn't a changeover is not permitted without penalty. So Tourte told Alcaraz that he could sit on the sideline and get help from a trainer, but he would need to concede the following game, which he did.
When play resumed with Djokovic ahead 2-1 in that set, the crowd jeered and whistled and booed, until Tourte explained in French what was happening.
"From that moment onwards," Djokovic said, "it was a different match.
"It was obvious that he was struggling with his movement. It's unfortunate for the crowd. It's unfortunate for the match of this importance for both of us. But that's sport."
Ruud will be playing in his third final at the past five majors -- including in Paris a year ago, when he lost to Nadal -- but is still seeking his first such trophy.
He swapped early breaks with Zverev before turning up the heat by pounding the German with vicious, spin-heavy forehands to go up 5-2 en route to claiming the opening set.
Zverev, playing in a third straight semifinal at Roland Garros, wasted an early opening in the next set and found himself in trouble as Ruud earned another break in the seventh game.
Ruud extended his lead in the match and continued to control the rallies from behind the baseline to frustrate an error-prone Zverev in the final set.
"It's going to be tough this year against Novak," Ruud said of the final. "I know Novak is trying to be the greatest. I'm going to try my best."
The Associated Press and Reuters contributed to this report.