Jonas Vingegaard climbed into the overall lead in the Tour de France on Wednesday with a mountain stage win for the ages as defending champion Tadej Pogacar wilted in the sizzling heat and cracked on the soaring heights.

On the day, Denmark's Vingegaard finished 59 seconds ahead of Colombian climber Nairo Quintana, while Frenchman Romain Bardet was third at 1min 10sec following the final climb to 2,413m altitude.

An exhausted Pogacar looked broken as he crossed the line seventh, 2min 51sec adrift at the summit of 11.5km ascent of the Col du Granon in the southern Alps.

Pogacar had the class to fist-bump Vingegaard at the finish line and was also big enough to face the media immediately.

"Suddenly I didn't feel well. It wasn't my day, but I'll keep fighting," promised the 2020 and 2021 champion, who lost two teammates to Covid-19 this week.

Pogacar dropped from first to third at 2min 22sec, after looking fine half-way up the final challenge.

Vingegaard now leads Team DSM's Bardet by 2min 16sec in the overall standings after he also soared on a tough, baking day.

Looking pale himself, Vingegaard expressed surprise at the extent of his triumph.

"Tadej is an enormous rider, the best in the world, he's won it twice, so to take the yellow off him like this is unthinkable," he said, then hinted that Thursday's proceedings could provide further drama.

"It's looking good for the upcoming stages, the plan was always to pile on the pressure on these two days," he said.

It was a first ever Tour stage win for Vingegaard, who finished runner-up in 2021. (AFP)