Nairo Quintana remains in the race leader’s red jersey after his Movistar team ambushed Chris Froome and Team Sky.
The Colombian dealt a body blow to the Tour de France winner when he joined a breakaway with Alberto Contador in the early kilometres of stage 15.
With six of his teammates at the back of the race the Brit was stranded.
Quintana and Contador had two teammates in the breakaway. They stuck the knife in by maintaining a lead throughout the stage of more than two minutes over Froome.
The Colombian eventually jumped away from Contador with Etixx QuickStep’s Gianluca Brambilla with one kilometre remaining.
Brambilla took the stage win, while Quintana, who finished 2mins 40secs ahead of Froome, now has a commanding overall lead of 3mins 37secs.
The Team Sky leader, who remains in second place, had a day he will surely want to forget.