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.
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Highlights: Djokovic downs Tsitsipas in five-set thriller
"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.
'Fantastic effort!' - Tsitsipas steals third set with brilliant winner down the line
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 looking forward to facing 'greatest rival' Nadal
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.
I look forward to it, I'm happy to be here and motivated to win.
'Just a joy!' - Djokovic digs out winner from behind him
'Djokovic could have wrapped it up in three sets' - Wilander
Eurosport expert Mats Wilander said Djokovic would be frustrated that he was kept on court for an extra two sets, with Nadal likely to pounce on any weakness.
"For Djokovic, that’s what he’s going to be disappointed with. He could have put this match away in three sets and he didn’t," said Wilander.
"He’s obviously physically strong enough but even a match like today will add up a little bit for Novak in the final."
Meanwhile, Tim Henman praised Tsitsipas for his fighting qualities.
"It was incredible. This whole event has been about expecting the unexpected," said Henman.
"With Djokovic in control – up match point – you thought it was done and dusted. But all credit to Tsitsipas, he hung in there and got back on level terms but it seemed he’d slightly run out of gas for the fifth set."