Chris Froome rose to the occasion to defend his Tour de France race lead on stage eight and the tricky finish of the Mûr-de-Bretagne.

The Team Sky rider accelerated hard on the tough uphill finale to secure eighth place across the stripe and maintain his 11-second hold on the yellow jersey.

Froome's effort on the third-category ramp put the peloton on the limit, with rival Vincenzo Nibali (Astana) losing touch, and only Alexis Vuillermoz (Ag2r-La Mondiale) and Dan Martin (Cannondale-Garmin) able to push clear.

The reward was a stage victory in Brittany for Frenchman Vuillermoz, with Martin coming home five seconds later and the chasing peloton another five back, led by Alejandro Valverde (Movistar).

Froome held on to all of his 11-second advantage over nearest rival Peter Sagan (Tinkoff-Saxo), with the GC picture set to evolve once again on Sunday.

With a key team time trial looming large on day nine Team Sky looked to ride an intelligent stage, conserving energy for much of the 181.5km test.

After the stage Froome put the day into context, confirming: "My team-mates did such a good job of bringing me into the foot of the climb in a good position. Once I hit the front I felt I'm here, I might as well just push on a little bit and see how the legs are feeling and also the response from the group behind.

"Honestly, I didn't try to show any dominance in the last climb. I was up there to keep a good position and to keep an eye on everyone, in case someone would jump. It was a relatively short climb and I knew there wouldn't be big differences. I wanted to stay at the head of the affairs.

"I was surprised to hear that Nibali lost contact, given that after the crosswinds it was easier to stay in the wheels with head wind.

"I knew the name of Alexis Vuillermoz but I don't know him personally. He has done a great stage. He attacked not only once but his second was a really strong one. He deserves his win. He's been impressive. 

"Today wasn't really about extending that gap, more about looking after the gap I already have. It's 11 seconds so it's not a big gap. But the main race is still to come. We've got the TTT tomorrow, then the rest day before we head into the Pyrenees and the real race for the yellow jersey starts.

"We really did try and approach the stage quite conservatively as a team given in the back of our minds we have the team time trial tomorrow. That's really quite an important stage for us. That's a day where half a minute could be won or lost depending on how it goes.

"It's going to be tough, especially with BMC breathing right down my neck and Tejay (van Garderen) right there. But we've got a really strong group of guys for the team time trial and hopefully we can be up there with the best.

"You definitely have to include Tejay van Garderen in the “Big Four”, which makes the “Big Five” now. He's done an impressive race until now. Not a long time ago, we were fighting for the win at the Dauphiné. There isn't much difference between us. He's in a great condition. Time will tell how he'll go in the mountains, in the Pyrenees.

"Nairo Quintana is a very strong climber. He has lost some time that he'll have to recover. Alberto Contador, we can never write him off. He never gives up. Vincenzo Nibali hasn't had the best start but we'll have to see him in the long climbs.

"Tomorrow's team time trial will be very decisive for GC. It's a tricky TTT. The course is undulating and we need five riders for the final climb. I expect substantial time differences.

"We see black riders at the Tour de France this year. I believe these athletes from East Africa have the best physiological abilities for endurance sports, including cycling. The problem is the infrastructures, the roads, the equipments… The federations are also a mess. It's wild there but there's a huge potential for development. In Kenya where I come from, there are projects that deliver interesting results already: the Kenyan Riders and the Safari Simbas that have played a role in my development too. They'll produce champions in a short period of time."

The pace increased in the closing stages, with Wout Poels and Nicolas Roche helping the team move up, before Richie Porte and Leopold König pushed hard on the final approach to the climb.

Geraint Thomas was the last Team Sky rider to pull off, selflessly emptying the tank to set up Froome, and dropping out of the top 10 overall in the process.

Froome drilled it on the front as the race headed under the flamme rouge, once again impressing during the opening portion of the race.

Earlier there was a brief moment of drama following a tricky uphill intermediate sprint as a select 17-rider faction went clear with 70km to go.

The peloton were forced to react and the increase in speed caught the day's original four-man break before the situation was brought largely under control.

A new three-man selection formed as Michal Golas (Etixx - Quick-Step), Bartosz Huzarski (Bora-Argon 18) and Lars Bak (Lotto Soudal) quickly opened out a minute on the peloton. That caused a hard battle, led by Cannondale-Garmin, as the peloton endeavoured to claw back the trio, eventually doing so with 8km remaining