Stefanos Tsitsipas became the first Greek player to reach a Grand Slam final after holding off Alexander Zverev's fightback from two sets down in a tense French Open semi-final.
After losing all three of his previous Grand Slam semi-finals, fifth seed Tsitsipas won 6-3 6-3 4-6 4-6 6-3.
Tsitsipas rediscovered his level in the decider, halting Zverev but missing four match points before serving out.
The 22-year-old faces Novak Djokovic or Rafael Nadal in Sunday's final.
Serbian top seed Djokovic and long-time Spanish rival Nadal, who is the defending champion and looking for a 14th French Open title, meet later on Friday.
After sealing victory with an ace on his fifth match point, Tsitsipas triumphantly raised both arms in the air before sharing a warm embrace with his opponent at the net.
The Greek then sat back on his chair to contemplate what he had just achieved before being overcome by emotion at the start of his on-court interview.
After taking a few moments to compose himself, Tsitsipas said: "All I can think of is my roots, and where I came from. I came from a small place outside Athens.
"My dream was to play here, to play on the big stage of the French Open one day. I never thought I would do it."
Tsitsipas overcomes wobble and 'intense' final set to win
Tsitsipas and Zverev have long been two of the upcoming stars in the men's game and when the 'Big Three' of Djokovic, Nadal and Roger Federer eventually retire, this promises to develop into one of the key rivalries for the sport's major honours.
Both young men have already won the season-ending ATP Finals and Masters titles in their burgeoning careers, but are yet to land one of the four biggest prizes.
Tsitsipas is now one more win from achieving that goal after preventing Zverev recording another memorable victory from a two-set deficit.
The Greek has been the leading player on the ATP Tour this year, winning more clay-court matches than any other player and claiming titles on the surface in Monte Carlo and Lyon.
Playing smartly and confidently, but without being truly tested by Zverev, Tsitsipas eased into a two-set lead.
Tsitsipas was dominant from the baseline as a lost-looking Zverev failed to change his tactics and was drawn into errors which he could not rectify until the third set.
Suddenly the German sixth seed improved his level and tightened up his game to haul himself level.
The first game of the final-set decider proved pivotal in the eventual outcome of the match.
Tsitsipas fought off three break points to hold serve, halting Zverev's momentum and going on to earn what was the decisive break in the fourth game.
"The opening game was nerve-wracking and so intense - it was the most important game in the fifth set," said Tsitsipas, who won in three hours and 37 minutes.
"I came back, stayed alive and had the crowd with me. They gave me energy.
"I still felt there was hope and opportunities to fight back. That's what I did."
Zverev unable to replicate US Open fightback
Unlike Tsitsipas, Zverev had already won a Grand Slam semi-final before, going on to lose to Austria's Dominic Thiem in last year's US Open final.
To reach his first major final in New York, the German had to fight back from a two-set deficit in his last-four match against Pablo Carreno Busta and threatened to do the same again at Roland Garros.
The possibility increased when he won the third and fourth sets courtesy of solitary early breaks which he backed up with solid serving.
For a player of such a young age, Zverev had already played a remarkable 23 five-set matches in his career. Winning 16 of those deciders showed he had the mental strength to cope with the pressure of another.
But, after that key opening game, it was Tsitsipas who found another gear.
Zverev showed incredible composure to bat off four match points on his serve in a lengthy eighth game, but could not break in the next as he was again unable to beat a top-10 opponent at a Grand Slam on the 10th opportunity.
"I'm not at a stage any more where great matches are something that I'm satisfied with," said Zverev.
"I lost. I'm not in the final. Was it a good match? Yes. But at the end of the day I'm going to fly home tomorrow. There's nothing positive about that."