17:00 - Thanks for joining us today - and be sure to check the full report for confirmation of all today's numerous incidents.
0km - Big casualties today included Denis Menchov, Thomas Voeckler and Chris Froome, who lost minutes at the finish. No change at the very top, with Wiggins still second behind Cancellara, despite being held up in that final crash.
0km - Such a dramatic end - but Sagan made it look so easy. He has time to goof around over the line. He finishes a few bike lengths ahead of Boasson Hagen, Velits, Cancellara, Albasini, Evans, Roche, Sanchez and Mollema in that order.
0km - Sagan takes the win! What an amazing finish! And another comic celebration - he does the running man over the line!
0.5km - Albasini and Evans are there ... BIG CRASH IN THE PELOTON ...
1km - Chavanel still out in front, but he looks exhausted. Here we go for the climb...
1.5km - It looks like Matt Goss is still in the group.
2km - Chavanel is tiring - but he has team-mates behind. Horner leads the main group for RadioShack.
2.5km - Sagan has Boasson Hagen on his wheel. Everything to play for on the final climb to the finish. Chavanel overshoots a tight right-hander - as does Valverde about 15 seconds later.
3km - BMC have four men on the front. Cancellara does not look too concerned - he's about 15 back. Chavanel has about 15 seconds.
4km - BMC are taking up the charge. Chavanel has about 8 seconds on the pack.
5.5km - Big attack by Sylvain Chavanel! The Frenchman powers clear and that will worry RadioShack - the Omega Pharma rider is just seven seconds down on Cancellara in the GC.
6km - Ivan Basso takes the points over the summit ahead of Tony Gallopin.
7km - Grivko, the last man standing, has now been caught. Cancellara, Evans, Sagan and Wiggins are all here. Nibali, Menchov, Van den Broeck and Vanendert too. But Voeckler is distanced, as is Gilbert. Valverde was, but is now back on. Cavendish has been dropped.
8km - Morkov has hit the wall and has been caught by the leading group. Grivko has just 12 seconds as he approaches the penultimate climb of the day, the Cat.3 Côte du Mont Lambert. There are about four further groups off the back chasing back on...
10km - Europcar's Pierre Rolland is present in the main chasing group, but not Voeckler. The rain has started to fall. Not heavy rain, but still rain. More carnage is likely.
11km - Morkov takes the point at the top. He's got maximum points on the first four climbs so far today to consolidate his polka dot jersey.
12km - The two leaders are onto the Cat.4 Côte de Quéhen with 40 seconds over the first chasing group.
13km - Both Cadel Evans and Bradley Wiggins are well placed in the first peloton chase group, alongside the yellow and green jerseys.
14km - Sebastien Minard and Ruben Perez have been caught by the pack, so we have just Grivko and Morkov out in front - and loads of riders off the back still.
15km - There are numerous groups off the back of the peloton. Dan Martin and Christian Vandevelde are in one, trying to get back with the pack.
16km - Problem for Alessandro Petacchi - he has a jammed chain and will have to wait for a bike change. Gilbert is in that second group behind the peloton - so his chances of victory today look slim.
17km - Grivko and Morkov are together but they just have 45 seconds over the bunch. There was a long flat section on the climb, but we're back onto a steep point. And it's Morkov who takes the point.
18km - The leaders are onto the Cat.4 Côte de Herquelingue - 1.7 kilometre-long climb at 5.8%. Grivko attacks and Morkov is dropped. The gap is just one minute back to the pack. Morkov fights back, but Minard is gone.
20km - Samuel Sanchez needs attention on his back wheel but is forced to see the Mavic neutral car because his Euskaltel car is nowhere to be seen. The Spaniard is livid that they cannot sort out the problem. It's not a flat, but the derailleur. All sorted eventually.
21km - The four leaders only have 1:15 now on the pack. There's a second group on the road containing the likes of world champion Mark Cavendish and France's Thomas Voeckler - another 1:10 back. RadioShack and Liquigas are driving the pace hard.
25km - Movistar's José Iván Gutiérrez is setting the pace on the front - just as he did after the first big pile-up. Not sure whether or not he knows that his team-mate Rojas is out of the race. Reportedly it's a collarbone problem.
26km - Jose Rojas (Movistar) has abandond the Tour de France.
28km - Vacansoleil's Johnny Hoogerland was involved in that crash too. The people on split in three now - with a big leading group, a chasing group of about 15 and another group off the back. Philippe Gilbert was not involved in the crash, but he was towards the back of the peloton and so was caught up. He's not back with his team car changing his shoes...
29km - BIG CRASH: Just as Gio Bernaudeau is being caught by the bunch, a load of riders go down heavily. Australian Simon Gerrans (GreenEdge) is one of those involved. Jose Rojas (Movistar) is also affected.
32km - The peloton cross the summit of this second climb 2:07 down on the four leaders. RadioShack and Liquigas still sharing the duties for their yellow/green interests - Cancellara and Sagan.
33km - Morkov jumps out of the saddle to take the two points over the summit ahead of Minard. meanwhile, back with the peloton, Argos Shimano's Marcel Kittel has been dropped. The young German is suffering from a stomach bug... He's not alone - lots of riders are being shed.
35km - The leading quartet have 2:30 on the bunch, which is being led by Liquigas rider Sylvester Szmyd. They're now onto the second climb of the day, the Cat.3 Côte de Mont Violette - 1 kilometre-long climb at 9.2%.
36km - ATTACK: Grivko decides its time for some action and leaps clear of the breakaway. He is checked by Morkov and the others follow, with the exception of Giovanni Bernaudeau.
38km - Now Movistar make their presence known on the front, through Jose Rojas. Sky are nowhere to be seen, presumably having to regroup after that blow. Losing Siutsou will dent morale in a big way - he's the first casualty of this year's race.
41km - The lead of the five escapees drops below three minutes. They still have five climbs to go before the finish. The peloton is back together after all those incidents. Both Tony Martin and Luis Leon Sanchez - who crashed heavily on stage one - are riding right on the back.
45km - Confirmation of the withdrawl of Kanstantin Siutsou of Team Sky. A big blow for Bradley Wiggins there, who has lost one of his key men. A broken ankle is suspected to be the cause.
46km - Ag2r-La Mondiale's Christophe Peraud was involved in that crash too - he's being paced back to the bunch by a cluster of team-mates. He's the joint leader alongside Nico Roche. Brice Feillu appears to be suffering too for Saur-Sojasun. Meanwhile, the lead of the six escapees is down to 3:20.
48km - Garmin pair Tyler Farrar and Christian Vandevelde were both involved in the fall there too, as was Lieuwe Westra of Vacansoleil. Sagan is back with a chasing group on the back of the peloton after his puncture.
49km - Kanstantin Siutsou is still down. He's sitting up but appears to have a problem with one of his legs. It looks like he won't continue the race.
50km - Green jersey Peter Sagan needs a bike change. The whole peloton has been blown open by that crash, which stalled much of the bunch. The race is now spread out in numerous echelons.
51km - BIG CRASH: A number of riders are down, including a Sky man and a Euskaltel man. It's Siutsou for Sky. He looks in pain and is not getting up. Pablo Urtasun of Euskaltel gets up and back on his bike after a while, but worries for Sky here.
53km - CORRECTION: It wasn't a series of punctures, as first reported, but a crash at a tight bend that was not picked up by the TV cameras. Initial news on race radio indicated punctures, but a number of riders were actually caught up in a spill. Nothing serious, mind. They are all back with the peloton.
55km - Astana's Vinokourov is also caught out and needs a wheel change. It seems like four or five of them picked up flats - Garmin's Robbie Hunter too.
56km - PUNCTURES: Astana's Andrey Kashechkin and Giro d'Italia winner Ryder Hesjedal (Garmin) both pick up flats and will need to fight to get back onto the back of the peloton.
60km - The leaders are now combining well to try to maintain their lead in this fast flat section between the climbs. They still have 4:30 on the pack. It will be interesting to see how close they come to holding on.
61km - Yaroslav Popovych (RadioShack) and Sylvester Szmyd (Liquigas) lead the peloton over the summit of this tiny hill. Off the back, France's Brice Feillu (Saur-Sojasun) drops a chain and needs to dismount to fix the problem.
62km - World champion Mark Cavendish is right in the middle of the pack for this climb. He'll struggle to be in a position to contest the finish today - he's just not built for these uphill drags and punchy sprints. Katusha are on the front as well now.
63km - Meanwhile, back in the bunch, BMC, Sky, GreenEdge and Rabobank have all crept up alongside RadioShack on the front. They're onto the start of the climb right now.
64km - Morkov takes the point over the summit, uncontested, to consolidate his lead in the polka dot jersey competition. Plaza leads the others over in second.
65km - Polka dot Morkov sets the place alongside Grivko. The real work of the day starts now - the rest has just been a warm up.
66km - The leaders are approaching the first of six small climbs that should start to animate this stage, the Cat.4 Côte de l'Éperche - 0.7 kilometre-long climb at 6.9%. The lead is 4:45.
70km - Spain's Alejandro Valverde drops back to see the mechanic. He seems to have a problem with his back wheel. The Movistar rider is one to watch at the finish today.
72km - Replays show Van Hummel coming across to cut off Cavendish, unintentionally. Cav has to check and then check again when Sagan takes Van Hummel's wheel. But the Brit still has enough power to recover and take the points - but before crossing the line, he looks back at the Dutchman and gesticulates wildly.
75km - GreenEdge have four men on the front as they approach the intermediate sprint - but it's Cavendish who takes the points for sixth place, ahead of Van Hummel and Sagan. That was quite a contest - almost like a mini bunch sprint. In fact, Cav was furious with Van Hummel for getting a bit too close. Goss finished best of the rest.
78km - Minard takes the points at the intermediate sprint ahead of Bernaudeau - but it was an uncontested affair. Morkov rolled over for third. In just under five minutes, there will be a scrap from within the peloton for the remaining points from sixth place onwards...
83km - Jens Voigt sets the pace. The 40-year-old father of six has an energy gel tucked up his shorts for a sweet boost a bit later on. Still, no real action to report on in north France. Who are your tips for the day? Have your say in the comment box below. 5km until the intermediate sprint.
86km - It's just under 10km until the intermediate sprint, with RadioShack leading the chase as a five-man break rides 4:40 further up the road. The leaders are: Ruben Perez (Euskaltel), Giovanni Bernaudeau (Europcar), Sébastien Minard (Ag2r-La Mondiale), Michael Morkov (Saxo Bank Tinkoff) et Andriy Grivko (Astana).
88km - Juan Jose Cobo spoke to Cyclingnews recently about the two riders he beat to the Vuelta crown last September: "Froome has come on a lot since last year but Wiggins even more. They're way further ahead than they were in the Vuelta and in the Dauphine I could see Wiggins was in a league of his own. His build-up for the Tour has been really impressive. If he keeps going at that level he'll be difficult to beat. He's like a robot. Right now, the rest are racing for second."
90km - This is the fifth time since 2000 that no rider has abandoned the race before the fourth stage. Last year Belgian Jurgen Van De Walle of Lotto was the first to abandon in stage 4.
92km - The lead continues to grow: the five escapees now have 5:05 over the pack, which seems to be taking a post-prandial nap.
95km - Fact from Infostrada Sports: If Peter Sagan wins today's stage he will be the youngest rider to win two stages in the Tour since René Vietto in 1934.
97km - The lead goes back out over four minutes as the peloton ease up going through the feeding zone. Maxime Montfort has just devoured an entire energy bar in one mouthful. Impressive.
100km - There's a slight rise in the road as the leaders pass through the feed zone, led by Ukrainian national champion Grivko. The stage will get going properly quite soon, what with the intermediate sprint and six climbs all on the horizon.
102km - Liquigas keep Sylvester Szmyd alongside the RadioShack riders on the front, while Team Sky take a breather off the back of the bunch. The gap has dropped below the four-minute mark to 3:50.
105km - The Liquigas team of green jersey Peter Sagan have now come to the front of the bunch. They will want to reel in the break to set up their man for the win today.
108km - Janez Brajkovic is receiving some treatment to his left elbow by the race doctor. Yesterday's incident with Bozic saw the rider catapulted from his bike, which was subsequently run over and pretty much destroyed by the commisaire's car. Nasty.
110km - Talking of Borut Bozic, the Slovenian was hit by a race organisation car yesterday from behind, and knocked off his bike. Apparently the car swerved into the Astana rider when trying to avoid hitting another car. Bozic hurt his elbow and had to go for hospital checks after the stage, which he finished in 17th place. Echoes of the Hoogerland-Flecha incident from last year - although this year we have no TV images and so we're in the dark with how bad it was.
114km - CRASH: Janez Brajkovic is down after a tight right-hander. The Slovenian is taken out by a falling Lampre rider and hits the deck quite hard. Luckily, the pace was low, so it should not be a repeat of his collarbone break last year. Brajkovic has his compatriot Boruz Bozic with him, plus Alexandre Vinokourov. He's up and back on his way.
115km - The first drops of rain are beginning to fall. Where Belgium was sunny, north France is cloudy, grey and overcast. There's a good chance of rain at the finish in Boulogne-sur-Mer and that would make it a hellish finale. It's going to be nervous as it is, but with rain fall, there could be carnage over the six climbs towards the end of the stage. No riders have quit the Tour so far - but that may, unfortunately, change by the end of the day. Yahoo weather report for Boulogne
117km - The entire RadioShack team is on the front of the peloton, with the exception of yellow jersey Fabian Cancellara, who is tucked in behind a cluster of Team Sky riders, in yellow helmets, a bit further back. The gap for the five leaders is now 4:10.
120km - Finally, Giovanni Bernaudeau is a 28-year-old Frenchman from Europcar riding his debut Tour. He is the son of team manager and former rider, Jean-Rene Bernaudeau, who finished second in a Tour stage on three separate occasions. Can his son go one better? Gio is the third Europcar rider in as many days to go on the attack in this year's Tour.
122km - Ruben Perez of Euskaltel is a 30 year old Spaniard riding his sixth Tour. He has one UCI win to his name, in the Tour de Baviere in 2010. Frenchman Sebastian Minard joined Ag2r last year from Cofidis. The 30 year old is riding his fourth Tour and is still in search of a stage win. He did, however, win the Paris-Camembert race in 2010.
124km - Grivko is the current national champion of Ukraine in both ITT and road race, it's worth adding.
125km - Let's take a closer look at some of the riders in this break. Andriy Grivko is a five-time Ukrainian national time trial champion riding his sixth Tour. The 28 year old from Astana came close to winning a stage last year but his six-man break was caught with kilometres to spare at the end of stage 11. Dane Michael Morkov is riding his first Tour and has made an impression with three breaks in as many days, plus the polka dot jersey. Not bad for the 27 year old Saxo rider.
130km - Speaking to Eurosport ahead of today's stage, Team Sky's Sean Yates said that Peter Sagan is the hot favourite for the win in Boulogne - but he has not discounted his rider Edvald Boasson Hagen to try his luck. The uphill sprint will certainly have some riders salivating with anticipation. One year ago, we would have said Philippe Gilbert was a shoo-in, but the Belgian has not been so dominating this year. His team-mate Cadel Evans might even have a pop, although Sagan is the man to watch.
135km - Europcar's Thomas Voeckler has probably been looking forward to today's stage since he saw it on the race profile. "It's a stage which could suit me well, but it's of interest for the whole Europcar team - and for all the other numerous riders who like these kinds of finishes. I will see if I can do something today - in any case, I'm definitely up for it."
140km - Morkov has already clocked up 345km in the lead of this year's race - chasing Jeremy Roy's 700+ kilometres out in front last year. Of the leaders, Giovanni Bernaudeau is the only Tour debutant, making a bow at the ripe age of 28. The lead is back up to just over five minutes.
145km - RadioShack combine to pull the lead down to about 4:10. In the battle for the yellow helmets, Team Sky are leading the race. The team of Bradley Wiggins and Mark Cavendish are four seconds ahead of RadioShack and six seconds ahead of BMC in the team standings. Team standings (yellow helmet competition)
150km - It's has been a much quicker start to today's stage, with the average speed of the five leaders 44kmh for the first hour. The gap has stabilised at 4:30.
151km - In the final of our jersey round-ups, Young American Tejay Van Garderen (BMC) still leads Norways Edvald Boasson Hagen (Team Sky) by one second in the white jersey youth standings. White jersey standings
152km - Tony Martin (OPQS) is riding with a broken scaphoid after his crash in stage one. "My feeling was not too bad, even if it was painful sometimes. The problem was when the road gets really bad and bumpy, there was small hits on the hand. It was a bit hard for me to control the bike, to brake and to have a stable position. So, today I survived, but I am concerned about tomorrow. I will also try to change a little bit the setup of my bike to find a more comfortable position for my hand."
155km - Team Sky DS Sean Yates was happy about Cavendish's win yesterday: "For the umpteenth time he’s proven that he’s the man to beat. He found the right wheel heading into the finish and you know if you give him half a chance and without bad luck, invariably he will strike. It was a tough finish today. We kept Bradley safe towards the front with Mark also up there. It was a perfect scenario for us as we have retained second place overall for Bradley and the guys are riding well together."
160km - The battle for the green jersey got rather spicy yesterday when Mark Cavendish's win over Andre Greipel put the world champion into second place in the points standings. Liquigas stage one winner Peter Sagan leads the Team Sky speedster by 78 points to 63. The intermediate sprint today comes before the six climbs, but it looks like these five riders might well still be out. The lead has dropped slightly, but is still a large 4:40. Green jersey standings
165km - It's French/Irishman Nicolas Roche's 28th birthday and the Ag2r-La Mondiale rider would certainly accept the stage win as a good present. "The end of the stage suits me well but I have to be more aware of what's going on," he told the Tour's official website. "In the stage to Seraing I tried to chase down the leaders a bit too early and I was no longer there to compete for the victory."
166km - Ruben Perez (Euskaltel), Giovanni Bernaudeau (Europcar), Sébastien Minard (Ag2r-La Mondiale), Michael Morkov (Saxo Bank Tinkoff) et Andriy Grivko (Astana) now have a lead of 5:40 over the peloton.
170km - There are two Cat.3 climbs and four Cat.4 climbs in today's stage - all of them in the last third of the race. Michael Morkov of Saxo Bank, who is in this break, is the current leader of the KOM standings. The Dane has four points, with both Pablo Urtasun (Euskaltel) and Peter Sagan (Liquigas) on one point. There is a maximum of eight points up for grabs today - two for the Cat.3 winner and one for each Cat.4 climb. Polka dot jersey standings
175km - The RadioShack team-mates of Fabian Cancellara have come to the front of the peloton to control the pace. Swiss maestro Spartacus has seven seconds over both Bradley Wiggins (Sky) and Sylvain Chavanel (OPQS) in the GC. He won't wont to lose the yellow to Grivko today, mind. Yellow jersey standings
180km - The lead of the five escapees is up to 3:45 now. They will need to get it as big as possible over the flat opening two thirds of the race if they want to stay out until the end today.
185km - Interesting to see Morkov in the group - that's three in a row for the Danish polka dot jersey, who definitely hopes to pick up some points in today's six climbs towards the end of the stage. Also, it's three-in-three for Europcar, who have the son of DS Jean-Rene Bernaudeau, Giovanni, in the break. On Sunday they had Johann Gene and yesterday Christophe Kern.
189km - The lead of the escapees is now two minutes. Grivko, who was the best-placed of them at 43rd in the GC at the start of the stage, is now the virtual leader of the TdF.
190km - David Millar had a flat tyre, but has returned to the peloton after it was replaced by the Garmin-Sharp team.
191km - A successful attack from five riders - they have a lead of 15 seconds. Giovanni Bernaudeau (EUC), Perez Moreno (EUS), Sebastien Minard (ALM), Michael Morkov (STB) and Andriy Grivko (AST) are the riders in question.
192km - No escape groups as yet as the peloton moves along at a very fast pace. Fabian Cancellara leads the GC after the prologue and opening two stages. GC
195km - The peloton catches up to them quickly however.
197km - There is an early attack from five riders at the start of the stage.
- - Yesterday Mark Cavendish ruled the reunion of the former HTC boys in a stage two sprint win over Andre Greipel. Blazin' Saddles on stage two
- - The Tour enters France for the first time today with the third stage starting off flat before peaking as Fabian Cancellara bids to hang on to yellow.