Holger Rune beat world number two Carlos Alcaraz 7-6 (8/6), 6-2 on Sunday to win the Barcelona Open for the first time.
Rune was nearly flawless as he became only the second player to beat Alcaraz in his last 23 matches on clay, although the Spaniard had some physical difficulties in the second set.
Four-time Grand Slam winner Alcaraz, gearing up for his French Open defence was hunting for his third title in Barcelona but came up short as Rune claimed his first anywhere since April 2023.
"It's a crazy feeling, it's been such a long time for me since I won a title, maybe a little bit more than a year, I'm so happy," Rune told TVE.
"To beat Carlos in the final, a good friend and an amazing player, means the world to me, I'm so proud to be in this moment.
"I think I was very composed, I played very tactically well again."
Alcaraz, who won the Monte Carlo Masters last week, drew first blood with a break in the fifth game but Rune hit back immediately to level at 3-3.
The Dane, ranked 13th in the world, put his opponent under heavy pressure in the 10th game, with Alcaraz forced to save two set points on the way to a tie-break.
Rune spurned two more in the tie-break before claiming the first set when Alcaraz went long.
It was the first set the Spaniard had dropped all week and he came out roaring in the second.
Rune saved two break points for a tough hold in the second game and Alcaraz won the third on serve before taking a medical time-out.
The 21-year-old rushed back out onto the court but ran into trouble, with the ruthless Rune breaking.
The Dane saved two break points on his way to consolidating for a 4-2 lead. Rune broke again and served it out, triumphing when Alcaraz slapped a shot into the net.