With the race leaders at the front towards the end of the 164-kilomtre route from Logroño to Alto de Moncalvillo, it came down to a straight contest between Slovenia's Roglič and Carapaz.

Jumbo-Visma's Roglič was the stronger rider, accelerating to cross the line 13 seconds before his Ineos Grenadiers rival and gain 17 seconds on the man in the red jersey in total, once time bonuses were considered.

Carapaz now has a 13-second lead in the general classification.

Ireland's Dan Martin, riding for Israel Start-Up Nation, came third on the stage and is third in the general classification, 28 seconds behind the leader.

Britain's Hugh Carthy of EF Pro Cycling had a poor day, being dropped towards the end and falling from second to fourth in the general classification, now 44 seconds adrift of Carapaz.

There is a noticeable gap between the top four and Enric Mas of Spain and Movistar, who sits in fifth overall but 1min 54sec back from Carapaz.

This is Roglič's second stage win on the 2020 Vuelta a España, as he seeks to overcome the disappointment of finishing second at the Tour de France.

"It was quite a boring, slow start and the pace went up and it was super fast and harder after the second to last climb," he said. 

"I always like to win, so if there is a small opportunity I will take it. 

"It was super hard today and luckily I had the legs and I'm happy to win the stage. 

"It's nice to get some time back but most of all it's nice to win the race."

Tomorrow's ninth stage is a flat one, with a sprint finish expected.