Rafael Nadal beat an out-of-sorts Roger Federer 6-3 4-6 6-4 6-3 at the French Open on Friday to reach his first Grand Slam final.
The Spaniard, who turned 19 on Friday, becomes the youngest men's finalist at the tournament since Michael Chang, who won in Paris in 1989 at 17.
Nadal, who is playing at Roland Garros for the first time, will now face Mariano Puerta in Sunday's showdown.
The Argentine beat Russian 12th seed Nikolay Davydenko in five sets.
Nadal's victory was his 23rd in a row in a season which has already seen him win five clay-court titles.
It also put an end, at least for another year, to Federer's hopes of becoming only the sixth man in history to win all four Grand Slam tournaments.
Friday's defeat was only Federer's third since August last year.
"It's incredible to be in the final and beat the number one in the world," said Nadal.
"Being in the final is a dream. I've just beaten the man who's the number one to me, not only for his tennis but also as a person."
A strangely subdued and tentative Federer never settled into a rhythm in an error-strewn opening set losing his service four times on the Philippe Chatrier Court.
"The simple version is that I started badly, finished badly and was good in the middle but that wasn't good enough," he said.
"It took me a set to figure it out. I'm not happy with my performance. I don't feel he was much better than me. I had the keys to beat him but I wasn't at my best.
"I'm not going to destroy the locker room and never play tennis again, you know. I'm not at that point.
"The motivation's big to come back the next few years and to do better."
The Swiss was broken in the first and fifth games as he quickly went 4-1 down, with point after point being squandered by a succession of wild forehands.
Federer broke back to 2-4 but then was broken again to slip 2-5 down with another loose forehand.
Nadal then squandered two set points as he surrendered the next service game to lead 5-3 but the world number one was unable to take advantage of this lifeline.
Federer was broken again in the decisive ninth game when he netted a simple volley and the opening set was Nadal's after 34 minutes.
Federer was out of sorts for much of the match
It was the first time in this year's tournament that the top seed had dropped a set but, in keeping with his position as the best player of his generation, he was soon back in the match.
He raced to a 4-1 lead in the second set with two breaks of Nadal's serve before Nadal stopped the rot in the eighth game to cut the deficit to 3-5.
But Federer levelled the match by taking the second set 6-4 when Nadal netted a backhand return.
A vicious smash gave Nadal a break and a 4-2 lead in the third set, only for the Spaniard to hand the break back in the next game.
But, three games later, Nadal engineered an advantage on his own serve. He pinned Federer back behind the baseline on his third set point and unleashed a brutal, running forehand to clinch the third set 6-4.
With the light beginning to fade, the fourth set went to serve for the first seven fames before a woeful Federer backhand gave Nadal another break to lead 5-3.
Nadal went to two match points and clinched a memorable victory after two hours 47 minutes when Federer hit another wild forehand long.