Chris Froome extended his Vuelta a Espana lead while Sander Armee spoiled Alexey Lutsenko's birthday by beating him to victory on stage 18 to Santo Toribio de Liebana.
A day after losing 42 seconds to Italian Vincenzo Nibali on the imposing ramps of Los Machucos, Britain's Froome broke clear of the depleted peloton 600 metres from Thursday's summit finish, with only Spaniard Alberto Contador and Canadian Michael Woods able to stick with him.
The Team Sky man took 21 seconds out of Bahrain-Merida's Nibali, moving his lead out to one minute 37 seconds with two tests to come before Sunday's parade into Madrid.
Dutchman Wilco Kelderman [Team Sunweb] sits third, two minutes 17 seconds down, 12 seconds ahead of Russian Ilnur Zakarin [Katusha-Alpecin] in fourth. Trek-Segafredo's three-time Vuelta winner Contador, in his final professional race, is fifth, three minutes and 34 seconds down.
Froome is bidding to become the first rider to win the Tour de France and La Vuelta in the same year since 1978.
Lotto-Soudal's Armee and Astana's Lutsenko were the final survivors of a 20-man breakaway as they came to the final climb at the end of the 169km stage from Suances.
Lutsenko, on paper, was the better climber, but the Kazakhstani did not have the legs on his 25th birthday as Belgium's Armee rode clear with 700 metres left to win by 31 seconds.
Friday's 149.7km stage will take the rides from the Parque Natural de Redes to Gijon.