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.

The gap is up to five minutes for this large 54-man break.

While three teams are not represented in this break, some have more than half their riders involved - indeed, more riders than FDJ have left in the race.

It's a clearer day today than yesterday, which was overcast and grey. The sun is out and the temperature is in the mid 20s. The Alpine views are, needless to say, quite breathtaking.

It's Colombia national day today so perhaps we'll see something special from the likes of Rigoberto Uran, Nairo Quintana, Carlos Betancur, Darwin Atapuma, Sergio Henao, Jarlinson Pantano and Esteban Chaves. Two of those riders - Atapuma and Betancur - are in today's break, which now has a gap of 4:30 over the pack. Remember, no Colombian has ever won the Tour de France although two riders have finished on the podium: Fabio Parra in 1988 and Quintana three times - in 2013, 2015 and 2016. Perhaps Uran could become the third this year - or even the first to win the whole thing...

We're running a series of Polls on Twitter today about your best Tour sprinters, climbers, time triallists and the like. Check our Twitter page for more...

We mentioned that Brice Feillu was the best placed rider in this break: the rangy Frenchman, a stage winner in Andorra way back in 2009, is 16th on GC but 33:32 down on Chris Froome. The gap is currently 4:40 for this break so Brice has a fair bit of work to do if he wants to win this Tour... (joke).

It's worth adding that just three teams are not represented in this break: Team Sky (who have bigger fish to fry and a yellow jersey to protect), LottoNL-Jumbo (who won yesterday's stage through Primoz Roglic) and Bora-Hansgrohe (who, er... that might explain why Marcus Burghardt was earlier trying to bridge across... it's not going to be pleasant tonight at the Bora dinner table).

The 54 leaders (thanks to letour.fr): Jan Bakelants and Cyril Gautier (AG2R-La Mondiale), Carlos Betancur and Jesus Herrada (Movistar), Bauke Mollema (Trek-Segafredo), Alessandro De Marchi, Amaël Moinard and Nicolas Roche (BMC), Andrei Grivko, Bakhtiar Kozhatayev, Alexei Lutsenko and Michael Valgren (Astana), Darwin Atapuma, Kristjian Durasek, Marco Marcato, Ben Swift and Diego Ulissi (UAE), Rudy Molard (FDJ), Daryl Impey (Orica), Stephen Cummings, Serge Pauwels and Jaco Venter (Dimension Data), Gianluca Brambilla and Zdenek Stybar (Quick Step), Robert Kiserlovski, Maurits Lammertink, Tiago Machado and Nils Politt (Katusha), Tiejs Benoot, Thomas De Gendt, Tony Gallopin and Jurgen Roelandts (Lotto-Soudal), Simon Geschke (Sunweb), Dimitri Claeys, Nicolas Edet and Dani Navarro (Cofidis), Thomas Voeckler, Lilian Calmejane, Sylvain Chavanel, Romain Sicard and Angelo Tulik (Direct Energie), Pierre Rolland, Simon Clarke and Andrew Talansky (Cannondale), Sonny Colbrelli and Tsgabu Grmay (Bahrain-Merida), Guillaume Martin, Marco Minnaard and Dion Smith (Wanty), Brice Feillu, Elie Gesbert, Romain Hardy, Eduardo Sepulveda and Florian Vachon (Fortuneo).

Froome has no Sky team-mates in the break; Uran has three in Andrew Talansky, Pierre Rolland and Simon Clarke; Bardet has two in Jan Bakelants and Cyril Gautier; Aru has four in Michael Valgren, Andrey Lutsenko, Andrey Grivko and Bakhtiyar Kozhatayev.

Team Sky lead the peloton for their man in yellow, Chris Froome. He leads Romain Bardet and Rigoberto Uran by 27 seconds on GC, with Fabio Aru dropping to fourth yesterday at 53 seconds, with Mikel Landa completing the top five at 1:24.

Those four riders have been joined by the chasing group so we have around 51 riders out ahead - the best placed of which on GC is Frenchman Brice Feilllu of Fortuneo-Oscaro. Serge Pauwels (Dimension Data) is there again, as are a host of usual suspects: Bauke Mollema, Sylvain Chavanel, Darwin Atapuma, Pierre Rolland, Simon Geschke, Cyril Gautier, as well as the originals in De Gendt, Calmejane, De Marchi and Gesbert.

Earlier today, Dutchwoman Annemiek Van Vleuten (Orica-Scott) won the fourth edition of La Course by Le Tour de France on the Col d'Izoard. Van Vleuten - who you may remember from that horrific crash during the Rio Olympics - attacked with 4.5km to go to cross the line 43 seconds ahead of British champion Lizzie Deignan and 1:23 ahead of Italian champion Elisa Longo Borghini. The second part of La Course will see the women riders take part in a pursuit-style time trial in Marseille ahead of the men's ITT on Saturday.

There's a big split in the peloton as around 45 riders zip off the front in pursuit of those leaders - with many of the GC men sending team-mates up the road as relays for later on. So many subplots to play out today, with multiple battles on the cards - for yellow, for polka dots, for the stage, and for kudos.

The indefatigable Thomas De Gendt (Lotto-Soudal) has opened up a gap along with Alessandro De Marchi (BMC), Elie Gesbert (Fortuneo-Oscaro) and Lilian Calmejane (Direct Energie).

The attacks come from the outset as the likes of Lars Bak (Lotto-Soudal), Thomas Voeckler (Direct Energie), Andrei Grivko (Astana) and Yukiya Arashiro (Bahrain-Merida) roll the dice.

And they're off! Christian Prudhomme waves his flag from the back of his red Skoda and the remaining 169 riders get this final day in the mountains under way...

Here's what's on the menu today - a long rolling opening schlep through the Alpine valleys and a loop away from Briancon ahead of a Cat.3 leg-stretcher, the tough Col de Vars and then the cherry on the top - the harder, southern side of the Izoard and its famous Casse Deserte.

Yesterday, Primoz Roglic (LottoNL-Jumbo) shrugged off an early crash and defied the mighty Col du Galibier to become the first Slovenian to win a stage on the Tour de France with a well-fought solo victory in Stage 17 in Serre-Chevalier. Chris Froome extended his overall lead on a day an injured Marcel Kittel was forced out.