Frenchman Julian Alaphilippe turned on the style to secure his first Tour de France stage win on Tuesday as Belgium's Greg van Avermaet stubbornly held on to the yellow jersey.
Alaphilippe, of the Quick Step team, launched an audacious lone attack on the third and penultimate climb and went on to solo over the finish several minutes ahead of the main peloton after a first day in the Alps marked by Van Avermaet outfoxing Team Sky in the yellow jersey stakes.
Days after France's World Cup victory, Alaphilippe handed the hosts their first win of the race - and soothed the personal pain of two frustrating years hoping to bag his first Tour stage win.
"I can't describe it. Going for a win like this was a big dream for me," said Alaphilippe, who twice came close to winning a stage on his debut in 2016 before being sidelined by injury in 2017.
"I've worked really hard for this. Not everyone realises how important it is for a cyclist to take part in the Tour.
"For a Frenchman it's simply unavoidable.
"I'm happy the last 10 kilometres was downhill because it gave me the chance to understand what was happening to me."
Expected to challenge overnight leader Van Avermaet for the right to wear the race's fabled tunic into Wednesday's 11th stage, the Sky team of champion Chris Froome failed to muster a challenge despite their best-placed rider, Geraint Thomas, sitting only 43secs behind the Belgian in the overall standings.
Van Avermaet, who is not a specialist climber, appeared under threat at the beginning of the 158.5 km race from Annecy featuring four categorised climbs and with a downhill finish into Le Grand Bornand.
But the wily BMC rider outfoxed Sky by joining an early breakaway that went on to build a healthy lead on the main peloton and stymie whatever plans Sky may have had of taking control of the race.
As Alaphilippe surged towards his memorable first win, Van Avermaet produced a fantastic performance to finish just 1min 44secs behind, with Thomas, Froome and Team Sky crossing the line over three minutes behind the stage winner.
In the overall standings Van Avermaet now leads Thomas, in second, by 2min 22secs, with Alejandro Valverde (Movistar) now up to third overall at 3:10.
Van Avermaet explained: "I was waiting for a reaction from Sky when I went to try and get in the breakaway, but nobody reacted.
"Once I was in it, I knew it could be a good day.
"Alaphilippe was too strong for me to hope to win today, but I'm happy finishing fourth.
"And I'm really happy to keep the yellow jersey another day."
Asked about his missed opportunity to take the race lead, Thomas said: "It would have been nice ... that's just the way it goes.
"Hats off to Van Avermaet, we kind of expected him to do that.
"It was a real strong ride from him, he deserves to have that jersey another day."
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Froome, who is bidding for his fourth consecutive Grand Tour win and fifth overall, is up to sixth place at 3:21.
The 11th stage, held between Albertville and La Rosiere, features four categorised climbs and the first summit finish of the race.
It is only 108 km long, and Thomas predicted fireworks.
"I think it will be racing full gas from the first climb," he said.
The third and final day in the Alps is on Thursday when sparks are expected to fly on the 14km climb, over 21 hairpin bends, to the summit of Alpe d'Huez.