David de la Cruz produced a bold ride to claim his first professional stage win and take the overall lead of the Vuelta a Espana in his homeland.
Nairo Quintana grasped the red jersey on Saturday, but it is De la Cruz who will go into the second week with a 22-second advantage after climbing to victory at the end of the 164.5 kilometres stage nine route from Cistierna to Alto del Naranco.
Etixx-Quick Step's De la Cruz was among a dozen riders to make an early breakaway and the 27-year-old got away from Dries Devenyns (IAM Cycling) on the final climb to win by 27 seconds.
De la Cruz leads Colombian Quintana (Movistar) by 22 seconds in the GC, with Alejandro Valverde 41 seconds adrift of the new leader in third place.
Team Sky's Chris Froome has 49 seconds to make up on De la Cruz, with Esteban Chaves (Orica-GreenEdge) 1:19 back and Alberto Contador (Tinkoff) just over two minutes off the pace back in seventh.
De la Cruz and a group of another 11 riders escaped early in the day and stretched their lead to four minutes and 30 seconds at the foot of the Alto de San Emiliano.
Riders had to contend with fog and cold conditions on the descent of San Isidro before Thomas De Gendt (Lotto Soudal) went out on his own up the Alto de Santo Emiliano, only to be reeled in 36km from the finish.
Devenyns and De la Cruz made their moves to open up a 20-second gap on the chasers with 8km to go and it was the latter who shot up the road to take a stage win that will see him start week two in red.
Moreno Moser (Cannondale) took third place, while Luis Leon Sanchez and Mathias Frank were fourth and fifth respectively.
It was pretty much as you were with the main GC contenders, with Valverde finishing a short distance ahead of Froome, Quintana, Contador and Chaves.