Britain No. 1 Jack Draper was beaten 5-7, 6-3, 4-6 by Casper Ruud in the Madrid Open final on Sunday.
The result means Draper's wait for a first clay-court title goes on while it marks the first Masters triumph for Ruud.
Draper's run to the final came without dropping a set and also saw him break into the top five world rankings for the first time.
He made a strong start to the final, going 5-3 up in the first set before Ruud went on a four-game run to clinch it.
The Briton refused to go quietly in the second, however, holding to love for 3-3 before breaking Ruud twice while making just one unforced error to force a decider.
Although Draper was more composed at the start of the third set, it was Ruud who seized the initiative, breaking the Briton to take a 3-2 lead and securing the title with a hold to love.
"I think you really deserve this," Draper told Ruud at the presentation ceremony. "You were braver than me in the key moments. This sport is brutal, but I think this loss is gonna make me better."
Information from Reuters contributed to this report.