The Danish Mitchelton-Scott rider attacked from a six-man breakaway on the final climb with 11 kilometres to go of the 189km journey from Gansingen.

He gained a 20 second lead and managed to hold off a disorganised chase.

Switzerland's race leader Stefan Küng was among those leading the pursuit.

The BMC Racing rider retained his overall lead despite failing to close the gap.

Juul-Jensen crossed in 4 hours 35min 56sec to finish eight seconds clear of the chasing peloton.

Michael Matthews of Australia and Team Sunweb was second while Belgium's Quick-Step Floors rider Yves Lampaert was third.

Slovakia and Bora-Hansgrohe's world road race champion Peter Sagan crossed fourth.

"It was a long three kilometres on the airfield here but it is a fantastic feeling," said the stage winner.

"I am over the moon."

The stage did not threaten the overall standings, where home rider Küng still leads a BMC Racing 1-2-3-4 after the opening team time trial.

Olympic road race champion Greg van Avermaet, Australia's Richie Porte and United States' Tejay van Garderen all lie three seconds behind in second, third and fourth respectively.

A 155.7km mountain stage from Gstaad to Leukerbad is scheduled for tomorrow.

The race is part of the International Cycling Union World Tour.