Greg Van Avermaet extended his lead in the yellow jersey with a superb ride as Julian Alaphilippe won stage 10 of the Tour de France.
Van Avermaet was expected to surrender the race lead he has held since the stage three team time trial as the race moved into the Alps, but the Olympic champion defied predictions as he joined a breakaway and stayed away on the road to Le Grand-Bornand.
The BMC rider crossed the line at the end of the 158.5km stage from Annecy fourth on the stage but around a minute and a half ahead of the main group of contenders, which included Team Sky's Chris Froome and Geraint Thomas, plus Adam Yates of Mitchelton-Scott.
Alaphilippe, 26, delivered his first career Tour stage win after moving off the front of the break at the summit of the Col de Romme, 28.5km from home.
The Quick-Step Floors rider gradually pulled away as he turned a bid for the climbers' polka-dot jersey into a first French stage win of this Tour.
After his BMC team-mate Richie Porte crashed out of the Tour on Sunday, Van Avermaet started the second week with no agenda but to stay in yellow as long as he could, and put in a ride to honour the jersey here.
He joined an 18-strong break that had moved seven minutes clear by the time they crested the summit of the Montee du plateau des Glieres, heading on to the gravel roads over the plateau made famous by the French resistance in World War II.
Sky were pacing the peloton behind but after slowing the pace to wait for Froome - who suffered a puncture on the gravel - they could not fully reel in the break.