Frenchman Julian Alaphilippe cracked at the top of the ascent to the Col du Galibier on Thursday, but a high-speed final descent in the 18th stage helped him regain contact with most of the big guns and retain the overall lead in the Tour de France.
The World No 1 sustained the pace in the climbs up to the Col de Vars and the Col d'Izoard, both culminating at more than 2,000 metres, but then lost ground when his compatriot Thibaut Pinot accelerated to rein in defending champion Geraint Thomas.
Deceuninck-Quick Step rider Alaphilippe, however, dug deep to limit his losses at the top and he took all the risks in the downhill where speeds reached 100 kph.
The gamble paid off as he regained contact with most of those challenging for his yellow jersey. Only Egan Bernal managed to narrow the gap with Alaphilippe as the Colombian leapfrogged defending champion Thomas into second place in the overall standings and is now 1:30 minutes adrift.
"I'm wounded, but not sunk," said Alaphilippe, who is hoping to become the first Frenchman to win the Tour since Bernard Hinault in 1985.
"It was a terrible stage as I anticipated. I gave my maximum and I want to thank my team who did a great job for me.
"In the finale, I gave everything I had but the attacks of Bernal and Thomas put me in the red, but I took risks in the descent to keep the jersey."
Alaphilippe, who shines in the classic one-day races and sometimes in the week-long events, has never raced for the general classification of a grand tour.
He is expecting to suffer even more during Friday's 19th stage, which features several punishing climbs over 126.5 kilometres.
"I take it day by day. It's a huge honour to be in yellow on the Tour and whatever happens tomorrow and the day after, I will be happy with what I have done," the 27-year-old said.
"I will try to hang on but it will not be easy."
