Dominic Thiem knocked favourite and 11-times champion Rafael Nadal out of the Barcelona Open with a stunning 6-4 6-4 victory in Saturday's semifinal, avenging his defeat by the Spaniard in last year's French Open final.
The Austrian will meet Daniil Medvedev in Sunday's final after the Russian also pulled off a surprise by edging out fourth seed Kei Nishikori 6-4 3-6 7-5 in a tight match.
Thiem had lost his last two matches against world No. 2 Nadal, first at Roland Garros then in the US Open quarterfinals in a thrilling five-setter, but he won their last meeting on Spanish soil, beating the Mallorcan in last year's Madrid Open.
The Austrian, ranked fifth in the world, broke Nadal to take a 3-2 lead in the opener and held in the next game thanks to a stunning cross-court forehand winner before seeing out the set.
He broke Nadal again in the fifth game to lead 3-2 and edged towards victory by taking a 30-15 lead before Nadal pulled himself back into contention by winning the next three points.
Thiem was serving for the match but Nadal dug deep to earn three break points only to lose each one, Thiem levelling the game with an ace after a marginal call from the umpire.
He sealed his fourth career victory over Nadal in 12 matches with a softly-struck backhand which the Spaniard had no chance of reaching, ending Nadal's chances of a fourth consecutive Barcelona Open title.
Twice Barcelona champion Nishikori beat Medvedev in the final of the Brisbane International in January but the Russian took an early advantage by breaking the world number seven in the seventh game.
Medvedev comfortably saw out the set but was pegged back by the Japanese, who won five games in a row to take the second set and make an ideal start to the decider.
Medvedev, ranked 14th, soon broke back to level the match and as both players consistently held their serve a tiebreak looked inevitable.
But Medvedev earned the first match point with a down-the-line winner and needed only one opportunity, clinching an entertaining match that lasted two hours and 25 minutes when Nishikori found the net with a forehand.
Sunday's final will be Medvedev's third of 2019 but his first final on clay.