Valverde finally responds as he goes through the 5km to go banner. A short burst of speed but he is still 23 seconds back.

That's a good sight better than Richie Porte though. He is 5'31" back and that is only going to get worse.

Insanity from the Astana rider. But there is no response from Valverde, or any of the other two riders he was with. Nibali quickly bridges to Majka and Konig. What will the Italian do next? Is he going to have a quick breather and then go again? He has 5km to the summit.

And what do I know? Vincenzo Nibali attacks.

The leaders have 7km of this hors categorie climb to Chamrousse to negotiate. Nibali is content to sit in Valverde's wheel. He knows he can just sit there all afternoon. It is up to Valverde, who started the day two minutes 47 seconds adrift, to try and break the Italian.

Majka and Konig are still out on their own up front but Valverde and Nibali, who have been joined by Pinot and Laurens ten Dam of Belkin, are just a dozen seconds back.

Richie Porte's hopes of finishing on the podium in Paris, never mind the top step, are disappearing today. He is two minutes, 40 seconds adrift.

Rob Hayles
Former Great Britain cyclist on BBC Radio 5 live sports extra

"It's every man for himself on this climb. No rider has a team-mate to help them anymore."

Here goes Alejandro Valverde. The man in third at the start of the day rides away from Vincenzo Nibali but the Italian responds and is soon in the Movistar rider's wheel.

Thibaut Pinot is not hanging around to see if Porte is coming back. The Frenchman puts in a burst of speed. Nibali appears untroubled.

Leopold Konig of NetApp Endura is the next to chance his arm and he is followed by Rafael Majka of the Tinkoff-Saxo team. Nibali doesn't need to cover either of those moves because they are not threats to his overall race lead.

Scrub that. team Sky's Richie Porte is going backwards. Vincenzo Nibali swings out to the left of the road and looks back down the road. The Italian must be loving this. The man in second place is going to be losing a lot of time.

Nieve has dropped back to help Porte but the Australian is weaving all over the road and has already lost more than 30 seconds.

Those in the leading bunch are: Mikel Nieve and Richie Porte (Sky), Alejandro Valverde (Movistar), Rafal Majka and Michael Rogers (Tinkoff), Vincenzo Nibali and Tanel Kangert (Astana), Bauke Mollema and Laurens ten Dam (Belkin), Jean-Christophe Péraud and Romain Bardet (AG2R), Rui Costa and Chris Horner (Lampre), Thibaut Pinot (FDJ), Jurgen van den Broeck (Lotto) Tejay van Garderen and Peter Stetina (BMC), Pierre Rolland (Europcar), Fränck Schleck and Haimar Zubeldia (Trek), Leo König (NetApp).

Chapeau Alessandro De Marchi. A terrific effort by the Cannondale rider but he is struggling to keep the pedals turning and as he looks over his left shoulder, he sees the peloton speeding up to him.

The Italian is quickly swallowed up and spat out the back. 13.5km to go. Who wants this the most?

Teardownyouridols:, external Lots of talk of Nibali wrapping up the GC today yet still a chance he could crash between here and Paris. Wide open race then.

Jan Bakelants has been caught as the riders go under the 15km to go banner. Just De Marchi left out front then and his lead is down to 30 seconds.

Polkadot Jersey
Classification

Has Joaquim Rodriguez hit the wall? The polka dot wearing King of the Mountains has dropped out the back of the yellow jersey group. Team Sky's Geraint Thomas is also struggling on this climb.

The chasing group is down to around two dozen as the relentless pace continues. Nibali riding third wheel with Richie Porte tracking his every more.

This final climb to Chamrousse then. It's 18.2km with an average gradient of 7.3%. Sections at more than 11% near the bottom.

Lieuwe Westra has gone. Nibali's helpers disappearing quickly. Movistar are now on the front for Alejandro Valverde and are now within 100 seconds of De Marchi. Who is going to be left at the finish?

Yellow Jersey
Classification

Race leader Nibali has only two men left to help him up this final climb - Lieuwe Westra and Tanel Kangert. But then Richie Porte only has Geraint Thomas and Mikel Nieve. The FDJ team of Thibot Pinot are pacing the peloton. They are 2'30" behind De Marchi, who has just hit the start of the final climb.

Rob Hayles
Former Great Britain cyclist on BBC Radio 5 live sports extra

"It wouldn't surprise me to see Nibali take some more time. I hope that doesn't happen. I want those behind him to take a handful of seconds and keep the race alive."

Image source, Getty Images

Stage leader Alessandro De Marchi is not quite on the final climb but he is going uphill. He has a motorbike for company with a photographer taking countless shots. He briefly climbs out of his saddle as he tries to maintain his lead, which is hovering around three minutes.

Rob Hayles
Former Great Britain cyclist on BBC Radio 5 live sports extra

"I would imagine we'll see the riders head up the right-hand side of the road because it's in shade and they will want to get as much respite from the sun as possible."

On race commentary, Rob Hayles says Jan Bakelants changed to a bike that would have been quicker on the descent and that it was worth him losing the dozen or so seconds to do so. He expects Bakelants to change again before we hit the final slope to Chamrousse.

Just 25km remaining and it's pretty much all uphill.