Top seed Novak Djokovic resisted a valiant and inspired fightback from Stefanos Tsitsipas to set up a French Open final showdown with old rival Rafa Nadal on Friday, winning a near four-hour battle 6-3 6-2 5-7 4-6 6-1.
Showing no sign of the physical problems that troubled him during his previous match, Djokovic was initially dominant and poised for a routine win when he had a match point at 5-4 in the third set.
But he had not counted on fifth seed Tsitsipas's incredible spirit as the 22-year-old fought his way back into contention with some dazzling shot-making.
Tsitsipas stole the third set as Djokovic faltered then staved off countless break points in the fourth before dragging the match into an unlikely decider.
His dream of becoming the first Greek player to reach a Grand Slam final faded away as Djokovic calmly re-asserted his authority against a physically-struggling opponent.
Djokovic sealed victory with a forehand winner, nearly two hours after his first match point.
The Serb advanced to his 27th Grand Slam final where he will meet Nadal for the ninth time in a Grand Slam final and 56th time in total.
Victory would earn him an 18th Grand Slam title while Nadal can match Roger Federer's record haul of 20.
While Djokovic, who had lost five of his nine previous French Open semi-finals, was given a fright it always looked as though his vast experience would prove decisive.
"We have to congratulate Stefanos for this great battle," Djokovic, whose sole French title came in 2016, said on Court Philippe Chatrier.
"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 in control."
Looking ahead to Sunday's final against 12-time French Open winner Nadal, he said: "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."
Tsitsipas, contesting his second Grand Slam semi-final, began by squandering three break points in Djokovic's opening service game and that became a theme for the Greek.
Djokovic broke serve in the next game with an angled forehand and fought off break points at 4-2 on his way to taking the opening set. The second set was one-sided after Djokovic broke in the fifth game and Tsitsipas became ragged.
World number one Djokovic bided his time in the third and broke serve at 4-4 with a dropshot-lob combination that had Tsitsipas scurrying around court all night.
But then things got complicated.
Djokovic missed a routine backhand down the line on match point in the next game and suddenly Tsitsipas began to offload with his punishing groundstrokes.
Tsitsipas finally converted a break point at the 11th time of his asking when a Djokovic forehand went long and then struck a forehand winner to break again for the set two games later.
Out of nowhere the match became a contest and after breaks were exchanged at the start of the fourth set, Tsitsipas dug deep to save break points at 2-2, 3-3 and 4-4 in the fourth.
Serving at 4-5 Djokovic led 40-15 but Tsitsipas clawed it back and Djokovic fluffed a dropshot attempt on set point.
Tsitsipas had required treatment on his legs in the fourth set and a clinical Djokovic was merciless in the decider, stretching his opponent with a succession of dropshots.
Djokovic broke at 1-1 with yet another dropshot and when Tsitsipas double-faulted to hand Djokovic a 4-1 lead his courageous challenge was over.
(Reporting by Martyn Herman, editing by Pritha Sarkar)
