Welcome to live coverage of stage 17 of the Tour de France, a 32km mountain time trial between Embrun and Chorges near the picturesque Lac de Serre Poncon in the Alps. Race organisers say this is one of the hardest race against the clock that they have come up with - and it features both two climbs and two descents.

Despite his injury, Peraud set the 17th best time at the first check, 52 seconds down on Valverde.

Alberto Contador is on course, so we have just the two riders left... Can Contador do anything to shake this Tour up today?

J-C Peraud almost comes a cropped on the first downhill, riding a corner wide and dangerously close to the verge. With his shoulder injury, it's the downhills that are going to be really hard for the Frenchman.

Roman Kreuziger is the first of two remaining Saxo-Tinkoff riders to roll down the ramp. He's got to be one of the favourites today...

We're into the top five now with Nairo Quintana rolling down the ramp. The white jersey from Movistar, on paper, should set the best time at the first split.

Laurens ten Dam of Belkin has started. The Dutchman dropped out of the top five yesterday.

Impressive from Andrew Talansky - the young American is third at the first check, 18 seconds down on Valverde and 20 seconds ahead of van Garderen.

Valverde had set the best time at the second check after the first descent: 15 seconds quicker than De Gendt. The Spaniard is going very well.

Next up is Joaquim Rodriguez of Katusha. He should ride well on this course - provided the weather isn't too much of a factor.

Jakob Fuglsang of Astana has started. The rain looks to have eased up now for the top ten.

Pierre Rolland to France2: "It was a good time trial but my problem was that it started raining when I was doing the first downhill. Seeing what happened this morning with Jean-Christophe [Peraud] I didn't want to take any risks and so I lost more than three minutes on that downhill. Tomorrow is a different day. Everyone knows that what Alpe d'Huez means to me after my win there in 2011."

It's the 110th time for Pierre Rolland, more than five minutes down on Van Garderen at the finish. He had three days in the Alps to save his Tour...

Jean-Christophe Peraud, who fell this morning in training to crack his collarbone, rolls down the ramp. This will be an hour of pain for the Frenchman...

New best time at the first check: Alejandro Valverde is 16 seconds ahead of Thomas De Gendt's target time - that's a huge 38 seconds quicker than the man who currently leads at the finish, Tejay van Garderen.

Dan Martin, the stage 9 winner, is on the road.

Richie Porte is taking this ITT pretty leisurely: he's 2'04 down on Van Garderen at the third split on the summit of the second climb.

Michal Kwiatkowski rolls down the ramp and we now have just the top ten riders left to start this second ITT.

Fourth quickest time for Andy Schleck at the first check, 18 seconds down on De Gendt. But it's the downhill that will test him...

Pierre Rolland is having a stinker: he crosses the third split at the top of the second climb more han four minutes down and in 119th position - which is slower even than non-climbers like Marcel Seiberg.

Tejay Van Garderen: "I felt ok, I just tried going through the motions. Usually when I do a time trial I'm concentrating on the GC but not today. It started to rain just on my second downhill, but the first descent, the more dangerous one, was dry. We'll see, maybe I have a chance of winning because of the weather. Froome will nto want to take too many risks."

Jean-Christophe Peraud is on the rollers, with his right shoulder bandaged. He crashed this morning in training and fractured his collarbone... but continues.