Italian Matteo Trentin won stage 10 of La Vuelta, as Nicolas Roche moved into a share of second-place.
The day's racing failed to affect Chris Froome's position as leader of the general classification, but did see Roche gain 29 seconds to join Esteban Chaves behind Froome.
"It wasn't really planned to go on the descent" says @nicholasroche. He took 29" over GC rivals pic.twitter.com/lQA7Q7bZP3
— Laura Meseguer (@Laura_Meseguer) August 29, 2017
The four-time Tour de France champion remains 36 seconds ahead of his closest rivals.
Ascending the Collado Bermejo, Trentin and Jose Joaquin Rojas formed a breakaway before the former ultimately pulled away to win his second stage of the 2017 event.
"For me, I wasn't willing to take any risks. I am in a good position in the GC and there was a lot of roads from the bottom of the climb to the finish," Team Sky's Froome said.
"We took it easy with my team-mates and kept everything together. Nico Roche wasn't a big worry for me.
"As I said, I was happy to stay safe, but he obviously did a great ride. He's in fantastic shape in La Vuelta, so congratulations to him."