Quintana was dealt a double blow on Wednesday afternoon. First, Froome stole a march in the closing kilometres to bolster his lead ahead of tomorrow's climb. Then, the ascent of Ventoux was cut short by six kilometres due to adverse weather conditions at the summit.
For Sky, the moment is coming when Quintana and Froome must inevitably go head to head. And while the British rider has the option of waiting for Friday's time trial to extend his lead, the Colombian has to attack soon.
"For the moment, we are really focused on Nairo," Sky sports director Nicolas Portal said. "OK, we are watching others too, but we can feel a big battle between those two.
"Because the time trial is the next day, Chris has two stages where he can be good and gain time. You don't want to give everything for the first day on Ventoux and then lose time in the time trial, because if you have a bad day, you have a bad day from the start to the end. The challenge is to go through the two days very well and try to gain time on both days.
"Nairo will be strong in the time trial, but not as much as Chris, so he might go hard on Ventoux. When you need to gain some time and you're a proper climber, you are not going to wait for the time trial if you have Ventoux beforehand. We are ready for him."
The 12th stage will race from Montpellier to Mont Ventoux, only covering 178 instead of 184 kilometres. Much of the punch has been taken out of the Giant of Provence with the often wind-swept and hot kilometres cut from the climb.
Watch: Cycling Weekly's guide to Mont Ventoux
On Friday, the Tour organiser has planned a rolling and technical time trial with a small climb to the finish in La Caverne du Pont-d'Arc.
"It's going to depend on how Froome feels on Ventoux. If he sees Nairo in a bad position, he will go if he can take time, but he will always have in the back of his mind that the next day will be an hour's effort. Real intense. It will be a big stage for Nairo. He needs to try to put Froome in a hard spot," Portal added.
"I don't know if Nairo will attack. In the last stage of the Andorra, he didn't attack, he just stayed there. If you are going well, you want to show yourself and try an attack to test yourself. It could be that he's not good or that he's saving himself for the last week."
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