What's the stage like?
It's another monster day in the mountains to match Stage 11. Three super-category climbs, an altitude high of over 2,600m, finishing atop the iconic Alpe d'Huez.
Expect a strewn-out peloton and more fireworks, and given how aggressive the General Classification riders have been, don't expect a breakaway to be successful.
Who are the favourites?
After blowing up the Tour on Stage 11, pre-race tip Jonas Vingegaard (4.47/2) is the obvious favourite to take another decisive win here. He is clearly in form, but thinking that dominance demonstrated one day is automatically carried over to the next is not always sound.
This is an equally difficult test, but is differently so, and different levels of cumulative fatigue may bring different results. Vingegaard is a likely winner, but is not a value bet.
Tadej Pogacar (6.05/1) is a tempting proposition. He'll be keen to re-establish his invincible status as soon as possible and - if he can - will no doubt try to attack at some point. It might be that the repeated efforts at altitude is what did it for him on Stage 11 and, with less time above 2,000m here, we may see him back to his best. Backing him is a risk, though, especially with a Covid-ridden team.
Thibaut Pinot (6.411/2) is prominent in the market. He reared his head on Stage 9, has seen a return to form this season, and has form on Alpe d'Huez, winning Stage 20 in the 2015 Tour de France. Whether he's quite returned to that level of form, however, is debatable, and those odds look skinny.
Who are the most likely outsiders?
Geraint Thomas (36.035/1) has looked short of the form on display from Pogacar and Vingegaard, but he's also been the one riding conservatively, recognising that this is a three-week race that is most likely to be decided during the closing days, not on some explosive climb in the first week.
Ineos are past masters at bringing their riders to peak at the right time in a Grand Tour, and given how exhausted his rivals may now be, it wouldn't be a huge surprise to see Thomas repeat his Alpe d'Huez win from 2018.
What effect will it have on the overall markets?
Like Stage 11, it will be pivotal.
*Odds correct at the time of writing