Roman Bardet claimed his first stage win in the Tour de France and moved himself into the top 10 overall on stage 18 as Chris Froome once again retained the Yellow Jersey for Team Sky.
AG2R's 24-year-old Bardet was involved in the day's early breakaway and made it his mission to win as he rode away and was the first to summit both the Col du Glandon and Lacets de Montvernier on his way to crossing the finish line in Saint-Jean-de-Maurienne.
Team Europcar's Pierre Rolland completed a France one-two 33 seconds behind Bardet, who was followed 26 seconds later by the chasing trio of Movistar's Winner Anacona, Trek's Bob Jungels and Rolland's Europcar team mate, Cyril Gautier.
Tinkoff-Saxo's Alberto Contador, keen to reduce his arrears in General Classification, launched attacks and was followed by Movistar's Nairo Quintana and Astana's Vincenzo Nibali. However all were caught by the rest of the peloton, although not for the want of trying.
Team Sky's Geraint Thomas said: "We knew the other contenders would be more worried about Contador than us so we let him go. We can see the finish now and Froomey's feeling good."
In a Tour where the King of the Mountains Jersey had been predominantly dormant on the shoulders of Froome and Joachim Rodriguez, the classification suddenly came alive with this performance from Bardet.
The competition now sees Katusha's Rodriguez on equal points with Bardet, 68, followed by Astana's Jakob Fulgsang on 64, Froome on 61 and Serge Pauwels of MTN-Qhubeka on 55, ripping the classification right open as the Tour heads into it's final two Alpine stages.
The 186.5km route was considered to be the hardest stage of the Tour so far, requiring those riders tough enough to survive seven categorised climbs including the Hors Categorie, Col du Glandon and a first ever visit to the Lacets de Montvernier, on their way through the Alps from Gap to Saint-Jean-de-Maurienne.
It was a relatively quiet day in GC, the only movement being Bardet's jump up into the top 10 replacing fellow French rider, Warren Barguil to take the albeit virtual title of best performing Frenchman in the Tour.
Contador did launch an audacious attack on the way up the Col du Glandon, however with the Spaniard 6'40" behind Froome in GC, the Tinkoff-Saxo man was allowed to go. He was joined by Quintana and Nibali soon after but was pegged back by the peloton on the descent towards the last climb of the day, the Lacets de Montvernier which has never been visited by the Tour in it's 102 year history.
Three minutes up the road from the Maillot Jaune group, Bardet was hitting the beautifully iconic hair pinned slopes of the Lacets de Montvernier, 40 seconds ahead of the chasing group of Astana's Jakob Fuglsang, Movistar's Winner Anacona, the Europcar pair of Pierre Rolland and Cyril Rolland and Trek's Bob Jungels.
Bardet went over the Lacets still with a 40 second advantage to the chasers but swiftly made it more like 50 seconds as he daringly swung round the corners on the descent.
Rolland, realising his chances of victory were quickly dissipating, broke from the chasers on the descent, desperate to catch his French counterpart before the finish line in Saint-Jean-de-Maurienne.
For all of Rolland's efforts though, he just couldn't close the gap and Bardet held on to take his first stage victory in the Tour de France.
Tomorrow is stage 19 and also the penultimate day for the Tour as far as the Alps go, although that certainly doesn't mean the terrain get any easier.
In fact arguably it gets tougher with a 138km route that includes Hors Categorie Col de la Croix de Fer from Saint-Jean-de-Maurienne to La Toussuire, the final climb being the one that Froome famously dropped Bradley Wiggins on in 2012 before being told to drop back by team management.