Nicolas Roche retained third spot in the Vuelta a Espana after Saturday's eighth stage but lost ground to the leader Chris Froome.
Roche now trails Froome by 41 seconds in general classification after placing 26th on today's stage. France's Julian Alaphilippe, meanwhile, signalled his return to top form after knee surgery and took his maiden grand Tour win
Britain's Froome, looking to become the first rider to achieve a Tour de France-Vuelta double since 1978, attacked on the final climb to extend his overall lead as only Alberto Contador could follow him.
Quick Step Floors rider Alaphilippe, who missed the Tour because of a knee injury, was part of the day's breakaway and followed Pole Rafal Majka's attacks on the final climb, a brutal ascent featuring gradients of more than 20 percent.
He was the quickest in the final sprint after 199.5 km, beating Slovenia's Jan Polanc (UAE Team Emirates) and Bora-Argon's Majka by two seconds.
"I did not expect to win the stage today. It was complicated as I did not feel that great. I was more thinking about tomorrow," Alaphilippe said.
In the group of overall contenders, Froome first appeared to struggle but only Contador could take his wheel when the Team Sky rider accelerated some four kms from the finish.
The duo gained 17 seconds on their closest rivals.
Froome now leads Colombian Esteban Chaves (Orica-Scott) by 28 seconds, with Roche (BMC Racing) a further 13 seconds behind.
Contador (Trek-Segafredo), on his final race before heading into retirement, is 17th, 3:10 off the pace after losing considerable ground in the first week but the Spaniard had been gradually climbing up the rankings since then.
