Colombia's Sergio Higuita of the Education First team won stage 18 of the Vuelta a Espana on Thursday as the overall leader Primoz Roglic came second in another assured step towards the title.
Podium pretenders Nairo Quintana and Tadej Pogacar however lost ground after a cat and mouse chase over a tough mountain stage.
Roglic chased Higuita across the finish line 15 seconds adrift alongside world champion Alejandro Valverde, who climbs back to second, and Miguel Angel Lopez, who produced the performance of the day.
Astana captain Lopez climbed fourth and more importantly reclaimed the white jersey as best under-25's rider after his relentless show of power had dropped Pogacar in their days long struggle for the white jersey also causing Quintana to crack.
Of all the contenders Lopez looks to have the most stamina with three days racing remaining.
Roglic now leads Valverde by 2min 50sec with Quintana third at 3min 30sec, Lopez fourth at 4min 17sec and Pogacar fifth at 4min 48sec.
Former Vuelta and Giro winner Quintana had powered back into contention on Wednesday reclaiming more than five minutes after a crosswinds caused a split in the peloton.
Thursday's stage embarked from Colmenar Viejo towards Becerril de la Sierra, a 177km run over four mountains on a cool day where Higuita was one of the early adventurers who struck out.
"I took a risk and it paid off," said Higuita, who showed great resistance over the final 10km as Lopez and Roglic closed him down.
With around 30km to go one of a string of strength and moral-sapping attacks on the final climb saw Quintana drop off the pace with Pogacar following suit a few kilometres later.
These two then joined forces to limit their losses and keep their ambitions alive.
"It wasn't my best day," admitted the 20-year-old Pogacar. "Maybe we can get something back on Saturday, that looks like the last chance," he said of the run through the Sierra outside Madrid.
The overall leader and former ski-jump champion Roglic gave a sign of growing confidence when the usually taciturn rider picked up a few bonus seconds on Valverde after outsprinting him in a showy dash to the line.