The two riders were part of a 30-strong breakaway on the 249-kilometre route from Vierzon to Le Creusot, with Belgium’s Wout van Aert, Italy’s Vincenzo Nibali and green jersey-holder Mark Cavendish of Britain also present.

While the latter unsurprisingly dropped back after earning more sprint points, the breakaway were able to build an advantage of more than seven minutes on the general classification group.

Race favourite Tadej Pogačar saw his UAE Emirates team unable to make inroads into the move, with the Slovenian left limiting potential losses.

Mohorič moved clear with 19km of racing remaining, with the Slovenian national champion going solo on the toughest climb of the day, the Signal d’Uchon.

The Bahrain Victorious rider remained clear to take an impressive victory in a time of 5 hours 28min 20sec.

He has now earned stage wins at all three Grand Tour races.

"This definitely is the best day of my career," Mohorič said.

"I’ve won stages on the two other Grand Tours.

"It has always been on the longest stage of those tours, the endurance effort suits my characteristics."

Mohorič finished 1:20 clear of Belgium’s Jasper Stuyven, with Denmark’s Magnus Cort leading a chase group over the line, a further 20sec back.

The group included yellow jersey Van der Poel, who arrived in the final kilometres with Van Aert after the two classics rivals had chased the riders together.

Several major time gaps were recorded between other groups, with world champion Julian Alaphilippe of France leading the general classification group at 5:15 behind the stage winner.

The group contained Pogačar, who admitted his team had made a mistake with the breakaway, but had importantly clawed back a potentially dangerous move from Ecuador’s Richard Carapaz.

"It was an unlucky moment when the break got away, a little bit our mistake," Pogačar said.

"Van der Poel and Van Aert are very strong and it’s dangerous to allow them to get a seven-minute advantage, even with all the mountains yet to come.

"We immediately tried to close the gap, but we didn’t manage to do it.

"From then on we did a great job, working and pulling together so they didn’t get too big of a gap."

Pogačar also expressed sympathy for fellow Slovenian and 2019 runner-up Primož Roglič, who lost nearly four minutes on the general classification group as injuries sustained in opening-week crashes take their toll.

Van der Poel now leads the general classification by 30sec from Van Aert, with Denmark’s Kasper Asgreen third at 1:49 back.

Mohorič and Pogačar complete the top five at 3:01 and 3:43 back.

Nibali was among the big winners from the breakaway, with the 2014 winner rising to sixth overall at 4:12 down.

Alaphilippe is 4:23 back, while Ineos Grenadiers' Carapaz and Geraint Thomas of Britain are outside the top 10 at 5:19 and 5:29 down.

Van der Poel’s advantage in the general classification is expected to take a major hit tomorrow, due to the challenging 150km mountain stage from Oyonnax to Le Grand-Bornand.