Thibaut Pinot emerged as the strongest of the main contenders to win the Tour de France after dominating his rivals for the second successive day in the 15th stage, a 185-km mountain battle won by Briton Simon Yates Sunday.
The Frenchman, who claimed victory at top of the iconic Col du Tourmalet on Saturday, left everyone gasping for air with a brutal attack seven kilometres from the finish in the final ascent to the Prat d'Albis.
He crossed the line 33 seconds behind Yates, who prevailed from the day's breakaway for a second stage win as his fellow Briton, defending champion Geraint Thomas lost further ground.
France's Julian Alaphilippe was among those dropped but he retained the overall leader's yellow jersey going into Monday's second rest day.
"It's not a surprise that I cracked against the best climbers at the end of the second week, having given so much since the start," world number one Alaphilippe, who has never raced for the general classification, told reporters.
Alaphilippe still leads Thomas by one minute 35 seconds, Dutchman Steven Kruijswijk by 1:47 and fourth-placed Pinot by 1:50.
Thomas's Ineos team mate Egan Bernal, of Colombia, who was the last rider dropped by Pinot, is fifth overall, 2:02 off the pace.
"We have a very strong team and our plan worked today, even if Thibaut's attack was not premeditated," his Groupama-FDJ sports director Yvon Madiot said.
"It was a very good Pyrenean leg. Now onto the rest day and the Alps. We're not setting any limit."
No Frenchman has won the Tour de France since Bernard Hinault claimed the last of his five titles in 1985.
Pinot, after some great work from team mates David Gaudu and Sebastien Reichenbach had put some rivals in the red, made his move seven kilometres from the top.
Thomas and Kruijswijk were dropped as Bernal crushed the pedals to join the Frenchman, taking Alaphilippe and German Emmanuel Buchmann in his slipstream.
But another burst from Pinot was fatal to Alaphilippe before Bernal and Buchmann eventually also lost the Frenchman's wheel.
Yates's advantage was, however, comfortable enough for the Mitchelton-Scott rider to take his second stage win this year.
Thomas saved his second place in the general classification with a late acceleration to finish 1:22 behind Yates and 51 seconds adrift of Bernal.