So, who are you backing for the stage win today? Who will cope best with the cobbles? Will Froome hold on to the yellow jersey?

BBC Radio 5 live sports extra commentator Simon Brotherton has gone for: John Degonkolb to win, Greg van Avermaert to take the yellow jersey.

Matt Slater has gone for the same as Simon.

Rob Hayles is backing Tony Gallopin for the stage win and can't make up his mind between Van Avermaert and Peter Sagan for the yellow jersey.

You can hear live commentary of the closing stages from 15:00 BST by clicking the relevant link at the top of this page.

Text me your thoughts on 81111. Or tweet #bbccycling, external

Matt Slater
BBC Sport at the Tour de France

"Some day soon we are going to get a nice, routine, first-week-of-the-Tour stage and we can all take a long lunch and change for dinner. It won't be today, though.

"The longest stage, seven sections of cobbles, wind, a forecast of rain and the certainty of sustained aggression.

"With Froome in yellow, earlier than expected, his rivals must stop Team Sky from gathering any more momentum.

"Nairo Quintana simply has to stop losing chunks of time, Alberto Contador could use a relative win and Vincenzo Nibali needs a repeat of last year's virtuoso demonstration of strength and skill.

"The Italian already has team-mate Lieuwe Westra up the road. The foundations for an attack have been laid."

Four riders broke clear from the peloton in the early knockings of today's stage and were allowed to build up a lead of approaching 10 minutes but they have been pulled back in to a more manageable two minutes.

The men in the break are: Lieuwe Westra (Astana), Thomas De Gendt (Lotto-Soudal) who initiated the breakaway, Perrig Quemeneur (Europcar) and Frederic Brun (Bretagne-Seche Environnement).

Westra is the interesting one because he is a team-mate of one of Froome's main rivals Vincenzo Nibali - and the Italian is decent over the cobbles.

The riders are already off and pedalling today and have completed around 100km of the 223km route. They are approaching the first of the seven cobbled sections and the pace is high.

True to Geraint Thomas's prediction, it's all about being first into the cobbles and the Team Sky train is right on the front of the peloton. They have around 5km to the first section. The remaining six all come in the final 50km

Image source, Tour de France

"Last year Team Sky didn't have the best of days on the cobbles, when Froome was forced to abandon, but personally I did pretty well. It's definitely a stressful day, but I enjoyed it and I'm looking forward to it again.

"If it's dry it won't be as bad, but if it rains like last year there could be big time gaps again. It's certainly a big day for the teams with riders competing for the overall victory.

"Everybody will be stressing about that and you've just got to concentrate on being in a good position at the front. The only problem is that's what 180 other riders want to do. It's all about fighting for position for when most of the cobbled sections start in the final 50km or so."

It is the longest stage of this year's race. A 223.5km (138.8 miles) ride from Seraing to Cambrai as the race leaves Belgium and crosses into France for the first time.

There are no significant climbs to negotiate today but what we do have is cobbles. Almost 13.5km spread across seven sections. If you've watched Paris-Roubaix and the one-day Spring Classics you'll be well aware of the chaos that the cobbles can cause.

If you're new to all this, you are in for a real treat today. Check out what Britain's Team Sky rider Geraint Thomas told us in his Tour de France stage-by-stage guide...

Marginal gains has been one of British Cycling saviour Sir Dave Brailsford's mantras over the years and it certainly paid dividends on stage three. But enough of stage three. That was so yesterday.

Today is all about stage four...

Image source, Peter Scrivener

Maybe Froome should have held back by 0.07 seconds. If he had been awarded a time one second behind stage three winner Joaquim Rodriguez, instead of the same time, Germany's Tony Martin would be in the yellow jersey today.

Rob Hayles
Former GB cyclist on BBC Radio 5 live sports extra

"Team Sky rode extremely well. Chris Froome, when he went with around 500m to go was very early but he set himself up to finish ahead of his main rivals and Alberto Contador was the big loser (finishing 18 seconds adrift of Froome).

"It's very early in the race for Froome and his team-mates to defend the yellow jersey. They have probably got themselves in this position without wanting it."

BBC Radio 5 live sports extra

Also on the podcast are our new race leader Chris Froome and his Team Sky boss Dave Brailsford.

Froome admits he is "surprised" to be in yellow and that "it's really early days".

Brailsford said getting the race lead was reward for "fantastic effort".

He added: "It's a big deal getting the yellow jersey, the most famous jersey in cycling and every time you get the opportunity to wear it you should respect it and be super proud of having it in the team and I know that's what we will be."

BBC Radio 5 live sports extra

Matt White, sporting director at Orica GreenEdge, told BBC Radio 5 live Sport Extra that it was "a fair decision" to stop the race. Several of his riders were caught up in the crash and he lost Simon Gerrans and Daryl Impey from his nine-man squad.

Britain's Simon Yates, who also rides for the Australian-based outfit, went down in the crash but he recovered to finish eighth on the stage.

"Rider safety comes first," said White. "These rules have to be taken on merit from crash-to-crash."

You can listen to more from Matt on the podcast.

Image source, Getty Images

The race was stopped for a little over 10 minutes to allow race doctors to attend to the injured, which caused a little confusion among those still riding.

Team Sky's Geraint Thomas said that he and a lot of the riders were not totally sure why the race had been stopped until they reached the finish.

But most people were in agreement that race director Christian Prudhomme had made the right decision in calling a halt to proceedings.

Prudhomme defended his actions, saying that although the main crash was "more spectacular than serious", the four ambulances and two doctors cars that follow the race were needed to treat the injured.

He added that he had no option but to stop the stage because "you must have medical assistance vehicles behind the race".

Image source, Reuters

Switzerland's Fabian Cancellara was the most high-profile casualty. It turns out the race leader, who was catapulted head first into a ditch, finished the stage despite fracturing two vertebrae in his back.

South Africa's Darly Impey was another to call it a day - although he rode the final 60km or so with a dislocated collarbone.

Australia's Simon Gerrans, Dutchman Tom Dumoulin, Dmitry Kozontchuk of Russia and France's William Bonnet, who sparked the chaos by being the first to come off his bike, are also out.

Andreas Schillinger of the Bora-Argon 18 team was also a non-starter this morning.

Image source, Reuters

Hello and welcome to live text and radio commentary (from 15:00 BST) of stage four of the 2015 Tour de France. It was another crazy Tour day on Monday with crashes, broken bones, dislocations, retirements and a tremendous finish up the impossibly steep Mur de Huy.

I'll move on to stage four after a brief look back at the carnage of day three which resulted in seven abandonments.

Yellow Jersey
Classification

Image source, Reuters

"I would much rather be in this position than having to make up time on my rivals," said British rider Chris Froome after surprising himself by taking the overall lead of the Tour de France on Monday's hectic third stage.