Remco Evenepoel lamented that he felt "a bit stupid" after Primoz Roglic pounced in the final metres to win the eighth stage of the Vuelta a Espana on Saturday.
On a good day for Jumbo-Visma, Roglic's team-mate Sepp Kuss took the overall lead of the race.
"It's really cool," said Kuss. "I'm happy to wear his jersey."
The trio were part of a small elite group that survived the final climb and then charged downhill to the line at the end of a mountainous 165km stage from Denia to Xorret de Cati.
When Evenepoel, famous for his finishing speed, attacked in the final stretch, Roglic responded and surged past for the stage win.
"I didn't know we were fighting for the victory," said Evenepoel. "I thought there was still a group in front."
The Slovenian, Evenepoel said, "wasn't really fastest."
"It's very frustrating, because I felt very good and I think I could win this stage. Probably the sports director said it on the radio and I missed it."
"I feel a bit stupid, actually."
Juan Ayuso finished third with a two-second gap before the next five riders including Kuss and the third Jumbo heavyweight Jonas Vingegaard crossed the line.
Roglic gained a 10-second bonus for winning. Evenepoel collected six.
"Some seconds lost to Roglic but some gained on others," the Belgian defending champion said.
Asked if the finish proved he was a faster sprinter, Roglic laughed.
"It's nice! Now I can be even more relaxed."
He added that he was happy to grab the victory.
"You always hope for the best," he said. "It's always a bit of a gamble in a sprint but I had the legs to do it."
Evenepoel survived a mass attack by Jumbo on the final climb.
With the group of leading contenders clear, Kuss attacked.
On Thursday, Evenepoel cracked when the American attacked on a mountain.
This time he dug in and gave chase with the two other Jumbo riders, Roglic and Tour de France champion Vingegaard sitting on his wheel.
"I kind of controlled it," said Evenepoel.
The Belgian caught the American at the summit and then led the brief downhill charge to the finish.
Lenny Martinez, who started the day in the overall lead, could not keep up and crossed the line 1min 10sec down.
He slid to third, a minute behind leader Kuss.
"The aim is not to lose too much time, but if I do, that's normal: there are champions up front," the 20-year-old Frenchman said. "I didn't want to explode on such a difficult climb."
Evenepoel ended the day sixth in the standings, 2min 31sec behind Kuss but seven seconds ahead of Roglic and 11sec clear of Vingegaard.
Jumbo has the race leader in Kuss and two Grand Tour winners lurking in the top eight. Roglic was asked how many contenders his team can boast.
"At least three now. But maybe still someone coming," he answered, laughing.
Sunday's stage is a hilly 184.5km run from Cartagena to Caravaca de la Cruz.