Tadej Pogacar beat fellow Slovenian and overall leader Primoz Roglic to win the 15th stage of the Tour de France as defending champion Egan Bernal all but abandoned his crown after a brutal failure on Sunday.
The Colombian was dropped 13km from the finish at the top of the Col du Grand Colombier, an unforgiving 17.4km ascent at an average gradient of 7.1 per cent, and lost seven minutes 20 seconds on the line.
Two-time runner-up and fellow Colombian Nairo Quintana also quickly lost contact with the leading group led by Roglic's Jumbo-Visma team mates, who set a frantic tempo from the bottom of the climb.
In the final 300 metres, Australian Riche Porte launched the sprint but Roglic and Pogacar followed easily and the younger Slovenian prevailed to win the punishing 174.5km trek in the Jura Mountains, for his second stage on his Tour debut.
Pogacar, however, was the freshest man in the finale, confirming he was the odds-on favourite's main rival.
An impressive Porte is enjoying a sweet resurgence, with this being the last year the 35-year-old will be competing as a GC contender at the Tour.
He finished third on the mountain-top finish - his best-ever stage finish was second in 2013 and 2015 - and is now sixth overall.
While too far back to challenge for race honours, the Tasmanian is a great position to match or improve on his best-ever fifth-placed finish in the race in 2016.
Rogic was appreciative of his teammates' support.
"Tadej is very strong, I have to say he has great legs," said Roglic ,who still had the support of teammates Tom Dumoulin and Sepp Kuss with two kilometres to go.
"My team mates did a great job today as I really wanted to win but I have to admit Tadej was slightly stronger."
Pogacar said it was a battle.
"Today was a tough day, Jumbo-Visma controlled the race and set super high temp. A lot of riders were dropped and I wanted to focus on the finale," said the 21-year-old.
Roglic leads Pogacar by 40 seconds and Colombian Rigoberto Uran by 1:34 as the race is turning into an all-Slovenian affair following Bernal's disappearance.
Bernal, who was third overall 59 seconds off the pace before the start in Lyon, dropped out of the top 10, meaning Ineos-Grenadiers, formerly known at Team Sky, will not win the Tour for the first time since Chris Froome crashed out in 2014.
They had won all the other editions since Bradley Wiggins became the first British winner of the race in 2012.
Bernal had been looking under par in the first part of the race and Sunday's stage confirmed that impression as the 23-year-old zig-zagged up the road, sweat dripping from his face, while Jumbo-Visma's Wout van Aert pulled the shrinking peloton.
"They were setting a really high pace. Nobody stood a chance," said Pogacar.
There was no coming back for the Colombian, who was paced up to the line by team mate Michal Kwiatkowski.
Adam Yates was the only rider to attack, seven kilometres from the summit, but the Briton's effort was short-lived as he was reined in seemingly effortlessly by the Jumbo-Visma led pack one kilometre further.