Novak Djokovic survived a heroic fightback from Stefanos Tsitsipas to book a final showdown with Rafael Nadal at the French Open.
The world number one looked set for a comfortable win on Court Philippe-Chatrier, only for the Greek fifth seed to belatedly splutter into action and force a fourth set - and then a fifth.
But there was to be no crowning moment for Tsitsipas, who could not rouse himself in the decider as he eventually went down 6-3 6-2 5-7 4-6 6-1.
Nadal earlier reached a 13th final in Paris with a straight sets win over Diego Schwartzman.
"We have to congratulate Stefanos for this great battle. In the end he was tired obviously, it was not easy after four hours," Djokovic said in his on-court interview.
"I was calm on the surface but inside it was something totally different. I thought that after losing the third set, and the fourth, I was still solid."
Djokovic cruised through the first two sets against a flat Tsitsipas, then broke serve at 4-4 in the third to have one hand on a ticket to the final.
But Tsitsipas finally awoke from his slumber to wriggle out of danger, upping the tempo on his groundstrokes to fluster the top seed.
In a sensational spell, the Greek fifth seed saved a match point, broke Djokovic, held serve, then broke his opponent again to earn the unlikeliest of fourth sets.
The pair traded breaks at the start of the fourth before Djokovic seized the ascendancy again, peppering the Tsitsipas serve only to blow eight break points on the spin.
Remarkably, Tsitsipas held serve to 5-4 and then repeated his heroics of the previous set to whip the reduced and socially-distanced crowd into a frenzy as the impossible comeback suddenly looked alive.
But that was where the drama ended. A wounded Tsitsipas, who had earlier had treatment on his thigh, ran out of steam as Djokovic reeled off six games on the spin to triumph in three hours and 58 minutes.
Djokovic will bid for a second French Open title, and an 18th Grand Slam, against omnipresent champion Nadal on Sunday and can ill-afford another two-set blip.
"Here, he [Nadal] is the favourite, it's his home here. With all the titles he's won... but in 2015 I won here against him in the quarter-finals," Djokovic said.
"I hope I can recuperate, I need my best tennis. It's maybe the biggest challenge in our sport to play Nadal at Roland Garros.