British hope Adam Yates has faded, Colombian Nairo Quintana is more than four minutes down and France's best chance, Romain Bardet, is peaking in sixth place.
That leaves classy Slovenian Primoz Roglic and Dutchman Tom Dumoulin. Of the two, Dumoulin is probably the only rider left who could potentially prevent Sky's leader Chris Froome from winning another Tour. He doesn't have a strong team around him but he can climb and time trial, and he has attacking flair.
In reality, though, Froome's biggest threat comes from within his own team. His top domestique, Geraint Thomas, is looking handy in the yellow jersey at 1m 39s ahead of second-placed Froome. Yesterday, he won his second stage of this Tour on the iconic Alpe d'Huez with a savage attack at the end. Afterwards, he played down his ambitions by saying he was still riding for Froome.
"He's still the man," he said. "This is unbelievable. Can we just go straight to Paris now?"
It would be a huge surprise if Thomas surrenders much of his 99s advantage to Froome in the Pyrenees. The Tour will be decided on the penultimate stage, a time trial near Biarritz. Thomas is a previous winner of the British TT championship. So it's an intriguing inter-team rivalry reminiscent of ... well, the 2012 Tour, when Froome feigned a mountain attack on teammate and eventual winner Bradley Wiggins, triggering a furious social media war between their girlfriends.
This week, Wiggins stirred the pot by saying Sky had "a real problem" with Thomas ahead on time.
Froome seems likeable enough. Yet despite being cleared by both the UCI and World Anti-Doping Agency for exceeding permitted levels of asthma medication salbutamol, the affair hangs over him like a bad smell.
Distrust is a big deal in cycling and Froome would not be a popular winner. He has been booed and spat on all along the roads of this Tour.
Competition for the other two big jerseys seem close to being decided. Frenchmen Julian Alaphilippe and Warren Barguil are vying for king of the mountains, while Peter Sagan has a near-unassailable lead of 210 points for the green sprinters' jersey.
Sagan, one of the great characters of professional cycling, will keep the green jersey, barring any incidents, and probably win most of the remaining five flattish stages after most of his sprint rivals became casualties of the Alps. Mark Cavendish and Marcel Kittel missed the time cut on stage 12, while Dylan Groenewegen, Andre Greipel and Fernando Gaviria all abandoned.
All that's left now is to enjoy the chateaux, mountains and rolling countryside of the world's longest free travel advertisement, and to wait and see if Sky's Froome or Sky's Thomas wins in Paris.