Movistar's Nairo Quintana landed a blow on Chris Froome and took possession of the red jersey following stage eight of the Vuelta a Espana.
Quintana attacked late on a brutal final climb on the 181.5 kilometre route from Villalpando to La Camperona, dropping Team Sky's Froome to gain 33 seconds on the Tour de France winner and take the leader's jersey from Darwin Atapuma (BMC Racing), who finished two minutes down.
Froome was passed by Alberto Contador (Tinkoff) before the line but remains third in the general classification standings, 27 seconds behind Quintana.
Quintana's team-mate Alejandro Valverde crossed the line with Froome and sits second in the GC standings, 19 seconds behind the Colombian.
Sergey Lagutin (Katusha) won the stage after holding off Axel Domont (AG2R La Mondiale), Perrig Quemeneur (Direct Energie) and Pieter Serry (Etixx-QuickStep) in the closing stages.
But the GC drama was just getting started behind them, as Froome was initially distanced by Movistar but fought back before launching an attack of his own.
Quintana kept pace, though, and then surged clear in the last kilometre of the gruelling Alto de la Camperona.
Contador's late attack earned him 12 seconds over Valverde and Froome and saw the three-time Vuelta winner move up to sixth in the standings, one minute 39 seconds behind Quintana.
Stage winner Lagutin told Eurosport: "I've been dreaming about it since I was little, to win a stage of a Grand Tour like the Vuelta, so when this happened I couldn't believe that it happened to me. I'm 35 years old and at some point I thought that it was probably it but I still hoped that it was for me."