Hello and welcome to live coverage of stage 18 of the Tour de France - the second of two Alpine stages that could well decide who ultimately wins the yellow jersey. It's a 179.5km ride from Briancon to the Col d'Izoard, where we will witness the first ever summit finish on this mythical climb.

Further back in the main body of the break - who trail the front of the race by about 1:20 - and there is some real climbing calibre. Riders to watch include Pauwels and Cummings of Dimension Data, Mate of Cofidis, Durasek of UAE Team Emirates, Roche of BMC, Talansky of Cannondale-Drapac and Gautier of Ag2R-La Mondiale.

Hardy, Edet and Lutsenko have opened up a small gap on this false flat to the foot of the climb. Behind, Ulissi and Molard have joined the chasers. Ulissi is a tidy climber, but doesn't have the stamina for something as relentless as the Izoard.

Dani Navarro is a good climber on his day - the only problem being the fact that his day was about a decade ago. The same could be said of Romain Sicard, who was once tipped to be the next big thing from the Basque region, but never fulfilled his potential at Euskaltel or Europcar beyond.

Of these eight leaders, the big danger man is the Colombian Darwin Atapuma - who was second over the top of the Galibier yesterday.

The four leaders are joined by Edet, Navarro, Grmay and Hardy so we have eight ahead now as they race up the Guil gorge towards the turn up the Izoard just ahead of the Chateau Queyras.

Since the Belgian Philippe Thys became the first man to scale the Col d’Izoard in pole position in the 1922 Tour, the race has returned to its daunting slopes and the eerie Casse Déserte on 33 occasions. Prior to the Second World War, Tour winners Henri Pélissier (1923), Sylvère Maes (1936) and Gino Bartali (1938) were all first over the summit en route to wearing yellow in Paris.

Descent over for the leaders, who reach the down of Guillestre. From here the road edges uphill and gradually gets steeper and steeper all the way to the summit. Game on.

Lutsenko, Atapuma and Sicard have joined Gallopin again on the front of the race. They have about 35 seconds on the other escapees and 5:55 on the Ag2R-La Mondiale-led peloton.

While the riders are on the descent it's a good time to look at this downhill primer from our friends at GCN: 6 tips for safer descending...

Tony Gallopin has edged ahead of the other leaders to open up a small gap on this descent of the Col de Vars. It's all a bit futile because the Frenchman is not renowned for his climbing and is bound to explode on the Izoard.

Belgian champion Oliver Naesen leads the Ag2R-La Mondiale-fronted main pack over the summit of the Vars, 6:35 down on the leaders.

Andrey Lutsenko zips clear to take the maximum 10pts over the summit of the Col de Vars for Astana. Gallopin is second ahead of Sicard and Atapuma. The Ukrainian has 1pt in the KOM standings and so moves on to 11pts now - and joint 21st place with Lilian Calmejane and Brice Feillu. And that's it: Warren Barguil's polka dot jersey is his unless the Frenchman crashes out of the race.

Sicard and Lutsenko has been joined by Darwin Atapuma and Tony Gallopin. They have about 20 seconds on the other escapees.

Five Ag2R-La Mondiale riders move onto the front of the peloton to spell the end for Luke Rowe's shift. Finally, Romain Bardet's team is taking it to Sky.

Romain Sicard (Direct Energie) puts in a big attack from the break and is joined by Andrey Lutsenko of Astana. The two open up a small gap as they edge closer to the summit.

The main pack is still being led by Team Sky with Luke Rowe - the Tour's Lanterne Rouge, more than four hours down on his team-mate Froome - setting the tempo. Dan McLay was the last man on GC until he withdrew through illness yesterday.

Pauwels is back with the break as Dani Davarro of Cofidis - also in yesterday's break - has a dig. Teisj Benoot of Lotto Soudal is near the front, too.

Serge Pauwels - who was very aggressive from the break yesterday - now leads the way on the Col de Vars, with numerous riders dropped: Clarke, Roelandts, Swift to name a few...

Attack from Nicolas Edet from the break. The Frenchman is followed by Durasek, Clarke and one of the Astana boys. But the gap is small.

The break is whittled down to 22 riders on the early slopes of the Vars as Team Sky controls the tempo back with the pack. So far, so uneventful today.

Time to get serious: the break moves onto the Cat.1 Col de Vars (9.3km at 7.5%). Straight away, riders are off the back while Serge Pauwels moves onto the front.