Hello and welcome to live coverage of Stage 12 of the Tour de France - a 175.5km ride from Bourg-Saint-Maurice to Alpe d'Huez via the Col de la Madeleine, the Lacets de Montvernier and the Col de la Croix de Fer. It's going to be as stunning as it is difficult.

Six of this large break have managed to roll off the front and into the lead. They are: Pauwels, Rolland, Gesink, Edet, Muhlberger and Postlberger. Belgian Serge Pauwels (Dimension Data) has been in all the breaks in the Alps and he could well move into the virtual polka dots over this summit if he stays out in front. It's him who is driving the pace.

Mikel Nieve came within 200m of a maiden Tour stage win yesterday - a win that will complete his Grand Tour hat-trick. All will be forgotten if he can do it again today - or if he there more as a foil for Mitchelton-Scott team-mate Adam Yates, who needs a good day today to revive his GC hopes.

So, it's a fascinating break - and one not without menace for Sky. Movistar have two riders including key man Valverde, while LottoNL-Jumbo have two strong Dutch riders in Gesink and Kruijswijk, the latter who is only 2'40" down on Thomas on GC. They may be there for a foil for Primoz Roglic, but Kruisjwijk is a threat in himself. In Rolland there's a former winner on the Alpe, plus a strong EF team-mate in Martinez - now both off the leash following Uran's withdrawal. Barguil won on the Izoard last year and needs no introduction, Latour is the white jersey and ally for Romain Bardet, Nieve almost won yesterday, Zakarin is no slouch and Majka has twice won the polka dot jersey before.

Julian Alaphilippe, the polka dot jersey, is one of the 26 leaders. The others are: Kruijswijk, Valverde, Zakarin, Nieve, Pauwels, Latour, Barguil, Majka, Mollema, Van Garderen, Moinard, G Izagirre, Rolland, Gesink, Gaudu, Martinez, Minnaard, Ten Dam, Amador, Edet, Sicard, Gesbert, Hansen, Muhlberger and Postlberger.

It's a huge break that has formed with around 20 riders holding a 30-second gap on the main pack, which has already reduced to around 50 riders. Names coming up once we have them.

Who is Sky's main man - Thomas or Froome? Our man Matt Stephens tried to get an answer from Dave Brailsford this morning...

Andrey Amador (Movistar) and Van Garderen lead a large group that bridges over. Team Sky are on the front of the pack monitoring the situation as a break starts to form. Sky are minus Wout Poels who has already been dropped.

Another attack from Warren Barguil, who rides clear of this lined-out pack. Behind, Majka dances out of the saddle to bridge over. Suddenly this is more promising: both former winners of the polka dot jersey.

The Frenchman sensibly sits up a little and waits for reinforcements. He's now on the front of a streamlined pack that is being driven by Marc Soler of Movistar. Laurens ten Dam of Sunweb is there, too, as is Robert Gesink of LottoNL-Jumbo and Rafal Majka of Bora-Hansgrohe.

Barguil is the only rider out ahead now - but surely it's way too early to go on a solo attack, even for a rider of panache like him.

Fortuneo-Samsic duo Warren Barguil and Elie Gesbert have opened up a small gap alongside the American Tejay Van Garderen of BMC. All three riders were involved in the big break yesterday.

Already many riders are in difficulty - most notably the sprinters such as Andre Greipel, which is no surprise. What is a surprise is seeing Domenico Pozzovivo seemingly feel the pinch. The Italian is a key support rider for compatriot and Bahrain Merida team-mate Vincenzo Nibali, fourth on GC. One of the riders who would be off the back if he hadn't already been kicked out is Mark Cavendish, who had this to say yesterday...

Right, show time. It's the Cat.HC Col de la Madeleine (25.3km at 6.2% to a height of 2,000m). The French wildcard teams - Cofidis, Fortuneo-Samsic and Direct Energie - are driving the early pace.

We're approaching the start of the climb and still we don't have a break - with the peloton averaging 60kmh so far on the largely downhill run to this opening uphill test.

Alpe d'Huez may be known as Dutch Mountain on account of the Dutch victories there back in the 70s and 80s but the last three riders to win atop the famous 21 hairpins have been French: Pierre Rolland (2011), Christophe Riblon (2013) and Thibaut Pinot (2015). Only one of those riders is in the race this year - that man Rolland... And to think that prior to 2011, no Frenchman had won on Alpe d'Huez!

Sylvain Chavanel of Direct Energie is the latest rider to ping off the front. But the 39-year-old veteran will know all too well that he will go nowhere without support. Perhaps we won't get a proper shake out until we start the first climb in a few kilometres.

There are 65 KOM points up for grabs today in the battle for the polka dot jersey - which means that someone who doesn't even have one point could still end up in the climber's jersey tonight because the tally of the current leader, Julian Alaphilippe, is 61. Serge Pauwels is second on 49pts and last year's winner Warren Barguil is third on 40pts. It's a bonanza day and so expect fireworks on the climbs.

Still no break has formed with Nils Politt (Katusha-Alpecin) now riding out ahead. He'll need support if he wants this to work.