16:25 - Thanks for joining us and be sure to return tomorrow for stage six.
16:25 - The big favorites - the likes of Contador, Nibali, Scarponi, Menchov, Garzelli, Kreuziger and Rodriguez - all finished in that chasing group.
16:25 - Weening will be the new race leader after David Millar's collapse. The Dutchman is two seconds ahead of HTC pair Marco Pinotti and Kanstantsin Siutsou in the GC.
16:20 - So, victory for Rabobank's Pieter Weening, with Fabio Duarte (Geox) taking second and Jose Rodolfo Serpa (Androni Giocattoli) third.
0km - Millar comes home with the man of the day, Martin Kohler of BMC, 2'49" down on Weening.
0km - Meanwhile, Millar's bloodied and bruised body is a picture of pain. It was all too much eventually for the Scot. He'll finish a few minutes down today... and lose the pink jersey.
0km - The bunch comes home just seconds later... phew, that was close!
0km - Pieter Weening holds on and takes the win! Incredible scenes...
0.4km - An attack by Euskaltel's Nieve. But it's going to be too late...
0.5km - Although the Dutchman is holding on. 500m to go and it looks as if the others have given up!
1km - Weening will be caught just after the one-to-go banner.
1.5km - ATTACK: Michele Scarponi turns on the gas and breaks clear. But Lovkvist closes him down, with Contador right there.
1.8km - Miller hits the wall! It's too much for the Scot, who is instantly dropped. Sky's Lovkvist is setting the pace, with Garzelli and Scarponi right behind. Contador is there too. And Kreuziger, Nibali et al.
2km - This is going to be terribly hard for Weening: at times there is a 10% gradient on this Poggio-style climb. Yes, the Dutchman has come to a virtual standstill.
2.5km - Here comes the final climb for Weening. Gadret and Kohler have been caught.
3km - Weening is really going for it. While Gadret and Kohler have almost been caught by the pink jersey group, the Dutchman is riding 40 seconds clear.
4km - The hilltop town of Orvieto is on the horizon. Not long to go now. But before the finish, a 600m punchy climb which willno doubt split the pack yet again. Will Millar hold on to pink?
5.5km - It remains to be seen if Weening has gone too early. He's opened up a large gap, but he maybe should have waited for Gadret there.
6km - Lampre have two riders on the front and Scarponi just behind. Also with three men are Sky: Kennaugh, Cioni and Lovkvist.
7km - The good news is that while Slagter remains on the floor, he has some forms of consciousness as his arms are moving and his legs are propped up. Relief there.
8km - ATTACK: Pieter Weening goes for it early, leaving Gadret and Kohler in his wake.
9km - The chasing group has three riders from Sky. Rabobank Slagter is still receiving medical attention. Our thoughts and prayers are with him.
10km - Kohler is caught by Gadret and Weening.
10km - CORRECTION: the Rabobank rider sufferign that heavy fall was not Brown, it was Tom Slagter. He's still on the floor and looks to be in a bad way.
10km - With the final climb a few kilometres away, Kohler will surely bite the dust soon. Both Weening and Gadret are good climbers and must be the favourites for today.
12km - Kohler still has 20 seconds over the two chasers. The bunch is about 50-strong and around 25 seconds further back.
14km - CRASH: A heavy fall on the back of the chasing group. It looks bad at first as the Rabobank rider is motionless. But thankfully he's moving now. That was worrying - echoes of Wouter Weylandt's crash which shocked the cycling world two days ago. I think it's Graeme Brown.
15km - Weening is back in touch with Gadret as they hunt down the Swiss BMC rider Martin Kohler, who has just 24 seconds now. The peloton are another 30 seconds back.
15km - Gadret has dropped Weening it seems. Kohler is only 40 seconds further up the road.
16km - Superb riding from Millar - he's riding himself back onto the chasing group. Maybe he will keep his pink jersey after all.
17km - Poor Kohler, it's not going to happen. There are two guys chasing him down. One of them is Rabobank's Peter Weening. The other is Gadret. Meanwhile, Marco Pinotti has a dig from the main group.
19km - Kohler's lead back to the chasing group - which includes the likes of Nibali, Contador, Garzelli and Kreuziger - is down to just one minute. Millar is trying his best to get back to the front... he's about 40 seconds further back.
22km - CRASH: Cataldo hits the deck on a bend, sliding across the dirt and gravel and into a ditch. He'll have some nasty road rash tonight. And then drama for Tankink, who drops a chain and needs a new bike. The Dutchman looks incandescent with rage as he's passed by the chasing group, led by Kreuziger.
22km - Terrible luck for a Sky rider, who needs a front wheel change. It could be Kennaugh. Meanwhile, the same happens to a Garmin-Cervelo rider.
23km - Kohler's lead drops to under two minutes. But he's really going for it still. The peloton is really strung out on this long descent into the valley. Millar is not too off the big group of favourites. Yes, he's a minute down on the chasing group, who are in turn 1'45" behind Kohler.
24km - ATTACK: AG2R's John Gadret leaps clear of the bunch. The French cyclo-cross man - and best friend of Nico Roche - decides it's time to test his legs.
25km - The main leading peloton is reforming on this second climb. Whittled down to about 50-odd riders. Cataldo and Tankink are up ahead chasing down Kohler, who has regained his composure. He has 2'10" now.
26km - The chasing group and peloton is scattered all over the place now. Popovych suffers a puncture and needs a wheel change.
26km - Lampre's Przemyslaw Niemiec and Quick Step's Dario Cataldo both overshoot a bend and almost collide.
26km - Bram Tankink (Rabobank) has attacked from the chasing group, which is riding 2'40" behind Kohler.
27km - Colnago's Domenico Pozzovivo overshoots a bend and is forced to ride round some road furniture and then under a barrier to get back onto the road. Nice skills.
28km - Kohler is onto the second section of the dirt roads. He has reportedly suffered a puncture though...
29km - Kohler's lead has dropped below the three-minute mark for the first time. It's going to be tight.
30km - Superb descending by Nibali! The Italian has opened up a lead on the front of the peloton thanks to some really dangerous moves on the dirt downhill. Behind him, one rider has unclipped and is using his legs and feet to stabilise himself on the corners. Vintage cyclo-cross racing, this.
32km - Kohler is back onto a small tarmac section. Race radio reports that one of the police motorbikes has toppled over on the descent. With those points atop the two climbs of the day, Kohler has moved above Brambilla in the mountains standings so he'll be rewarded with the green jersey tonight.
33km - This is a very dangerous descent, made all the more difficult with the levels of dust. Kohler will like the fact that he's out in front - it must be hellish sliding around all over these dirt roads as part of a big group or peloton.
35km - Over the top comes the peloton, 3'25" behind leader Kohler. Sky's Peter Kennaugh, riding his first major tour, is in touch with the leaders. Chapeau to the Manxman. Pink jersey David Millar is 20 seconds or so down.
36km - The bunch has been blown apart. Kreuziger leads Scarponi and Garzelli. Nibali and Rodriguez are there, but some of the other big names are feeling the pressure.
36km - Popo is going to be caught, but his move has really opened things up. The road is so dusty. You lose your sun glasses out there and you're doomed. They have reached Popovych. Kreuziger is right up there. He's my tip for the podium this year.
37km - Riders from Astana and Rabobank try to follow Popovych. Scarponi and Rodriguez have moved to the front...
37km - ATTACK: Yaroslav Popovych breaks clear from the peloton. On the front, Kohler is pedalling squares. He's really hit the wall. This is an almighty bonk.
37km - Movistar have moved forward too. The bunch has yet to hit the dirt roads but will do imminently. Kohler is really suffering on the front. But what a stellar ride this has been from the Swiss. He's almost come to a standstill though! This is brutal...
38km - The Astana team of Roman Kreuziger have moved on to the front of the peloton. Kohler's ride has been admirable - and he's holding on for longer than Sean Kelly thought he would.
38km - Besides the dust, the obvious difficulty on these dirt roads are punctures and visibility. They have 19km or so to cover in this first section.
39km - Martin Kohlner (BMC) is currently riding out in front 5'50" ahead of the peloton. The lead was 12'30" but has slowly been whittled down. And he's now onto the dirt roads...
40km - So, here come the white dirt roads - or strade bianchi - of the south Tuscan hills. These roads are not usually used by cyclists - or even cars. They are access roads for the local farmers. Last year, on stage seven to Montalcino, the heavens opened reducing the dirt roads to one big mud bath. This year the sun is out, so the problem will be dust and not sludge. Bring it on...
42km - CRASH: There's a low-speed pile up in the peloton. Quite a few riders are involved, including AG2R's Cyril Dessel and Vacansoleil's Johnny Hoogerland. That has created loads of little splinter groups in the peloton.
43km - Liquigas, Saxo Bank, Lampre and Garmin-Cervelo are all towards the front now. It's a hot day in Italy. At the finish, it's 25 degrees and very sunny. Orvieto weather report
44km - Kohler is on to the start of the second major climbs of the day. He's struggling now, understandably. The lead is down to 6'44".
45km - Saxo Bank's Richie Porte, the revelation of last year's Giro, was involved in one of those crashes earlier. His team-mates are busy protecting Alberto Contador and so have not been able to help the Australian back to the front. The first of the white dirt road sectors is coming up in seven or so kilometres.
48km - CRASH: Vasili Kiryienka (Movistar Team) comes down after touching wheels with another rider. He's ok, but it shows just how nervous the riders are out there today...
50km - The first three over the last third-category climb were Kohler, Gianluca Brambilla (Colnago-CSF) and Christophe Le Mevel (Garmin-Cervelo). Brambilla is the current green jersey holder as best climber.
50km - Kohler is maintaining his gap: 7'24" at the latest check.
52km - CRASH: A RadioShack rider and a BMC rider hit the deck on a fast bend. The BMC rider is the USA's Chris Butler. He's back on his bike, but looked pretty shook up.
55km - Impressive crowds out beside the roads of Italy. They love their bike racing, do Italians, but I'm sure the tragic circumstances of the last couple of days have galvanised fans. Yesterday's tribute stage to Wouter Weylandt showed just what a special sport cycling is, and how fervent and loyal are its followers.
60km - Kohler, riding 7'20" out ahead, stretches his legs on a descent. On the back of the peloton, Omega Pharma-Lotto's Sebastian Lang, turning a huge gear, looks to be struggling on a small rise. That seven-man breakaway has been reeled in by the peloton, so it's just the lone Swiss rider out ahead.
65km - Katusha are moving to the front, as are Colnago. The Italian pro continental outfit want to control the lead of the mountains jersey Gianluca Brambilla.
68km - Garmin-Cervelo - including a road-rashed pink jersey David Millar after that freak crash moments earlier - are on the front of the peloton controlling the situation. They won't want those seven riders out ahead to build up too much of a lead. Kohler's lead is down to 7'38".
71km - The five chasing riders have opened up a 30 second gap over the peloton. Two more riders look to join them ahead. Names coming up...
72km - Aramendia is joined by four riders on a descent so there are now five out ahead in pursuit of lone leader Kohler. The first man to catch the Euskaltel rider was Ag2R's Rinaldo Nocentini, who appears to hold one nostril and, ahem, clear his nose in the direction of Aramendia as he passes. We'll forgive him: the Italian has been suffering from bronchitus this week.
75km - Just to note that the three white road sections come with 37km, 25km and 21km to the end of today's stage.
75km - ATTACK: Euskaltel's Francisco Aramendia tries his luck on this early climb. He's opened up a small lead as the peloton adapt to that earlier collision.
76km - That's a sight you hardly ever see. A totally unnecessary crash there - and surely the result of a lot of nervousness from the part of Millar. Vicioso wasn't at fault - he clearly had no idea that Millar was on his left - but the Spaniard did drift to the left of the road, and the collision was inevitable. Vicioso is the more knocked up of the two. Millar has a lot of road rash, but he's back into the peloton now. Drama...
78km - CRASH: Pink jersey David Millar and Angel Vicioso collide and hit the deck while sprinting for the intermediate check. There was six seconds up for grabs for 2nd place behind Kohler and Vicioso, just seven seconds down on Millar on the GC, went hell for leather. Millar took his wheel, but the two knocked shoulders and fell at pace.
80km - Seeing that Kohler is 50 seconds down on the GC, it's unlikely that he'll be able to stay out in front till the finish today. On TV, Sean Kelly just said that for a lone rider to be able to finish ahead on a stage as demanding as today, he'd need a maximum lead of around 20mins. Today, Kohler peaked at 12'30". But with the riders of Androni Giocattoli upping the pace on the front of the peloton - possibly in pursuit of red jersey points for Angel Vicioso - Kohler's lead is dropping.
85km - Kohler is currently riding at 8'45". He's on to the lower slopes of these approaching hills. The Swiss rider passes through the intermediate sprint at Arcidossa to pick up maximum points.
90km - Listen to LIVE commentary from David Harmon and Sean Kelly (this is Eurosport International not British International): click here for audio
90km - Talking of Sciandri, the BMC directeur sportif has been speaking to Italian TV. Apparently Martin Kohler's attack was planned by the US team, who have identified today's stage as a possible win. Meanwhile, on the front of the peloton it's the Garmin-Cervelo team of David Millar which is setting the pace.
95km - Well done to all of you below who correctly identified Bradley Wiggins as the other British rider -alongside Cavendish and Millar - to wear the pink jersey. For any of you who thought perhaps Max Sciandri was the answer, think again: the Italian born British rider did not take up British citizenship until 1995 and I think his maglia rosa came three years earlier.
100km - The lead is down to nine minutes.
110km - The riders pass through the feeding zone. Soon the climbs will begin.
120km - Kohler's lead is down to 9'15" as he zips through a valley en route to those dirt tracks and the stage's iconic climbs.
130km - David Millar took over the leader's maglia rosa in the most horrific of cicrumstances on Monday. What should have been a celebration must have been a huge burden for the Scot, who carried out the duties of the race leader admirably in the wake of Wouter Weylandt's tragic death. Millar took over the lead from Mark Cavendish - but who is the other British rider to have worn the pink jersey during his career? Answers below please...
135km - So, who is Martin Kohler? The 25-year-old Swiss BMC rider is riding his second Giro d'Italia - although it could effectively be classed as his first: Kohler retired in 2010 in stage two after suffering a nasty fall. With no professional wins to his name, Kohler raced in these parts in March's Strade Bianche race, won by Philippe Gilbert. He finished 52nd. A solid ride today could be the making of him.
140km - Kohler's lead has dropped a minute after a punchy climb, but the Swiss rider is looking good.
145km - The average speed for the first hour of racing today has been 45.2km/h.
150km - Meanwhile, back on the road, lone escapee Martin Kohler of BMC has increased his lead over the peloton to 11'50". The road has been largely flat so far, but there's a small peak on the horizon, before the undulating stuff comes along after the feeding zone.
155km - And finally, Leopard Trek sent out a message on Twitter this morning: "To all the teams that stayed in the Giro d'Italia: Put on a great race and come back home healthy!" Read more: Rivals back Leopard-Trek withdrawal
160km - On withdrawing from the race, Leopard Trek announced the creation of a donation account to help Wouter Weylandt's family following his tragic death. All funds will go to the family to help Weylandt's partner An-Sophie, who is due to give birth to the couple's first child in September. Further details can be found on the team's Facebook page.
165km - More on the Leopard Trek withdrawal today. Team leader Fabian Wegmann said: "We have great respect for the Giro and its history, but we really cannot race under these circumstances. We know that we are all professional athletes but we think that this is the right thing to do." General Manager Bruian Nygaard on the poignant moment on yesterday's podium: "There's no use talking. We saw how powerful the passion for cycling and the support of the people can be."
170km - Lone leader Kohler has just passed the town of Follonica with a lead of 4'50" over the bunch.
175km - The finish is incredibly demanding, with a 12% uphill section for 600m around 2km from the finish in Orvieto. The last half kilometre into the Tuscan hilltop town is pretty much flat, so if there's a selection of riders left, expect a competitive sprint to settle the spoils. Whatever happens, we should see a new pink jersey today - unless David Millar has a stormer.
180km - Last year's stage over the hilly 'strade bianche' chalk roads in Tuscany was pretty eventful: a crash in the peloton took out three Liquigas riders, including then-pink jersey Vincenzo Nibali and eventual winner Ivan Basso. Meanwhile, up the field, the likes of Cadel Evans, Alexandre Vinokourov and Damiano Cunego battled it out through the sludge with the Australian taking the stage in Montalcino. There will be no sludge today - but think of Paris-Roubaix, where the dust can be just as bad...
185km - An early attack by BMC's Martin Kohler, who has quickly opened up a 45 second gap over the peloton. It's great to see the race return to 'normal' circumstances. There is always a fear after something as tragic as Monday that riders will hold back. But the spirit of cycling lives on. Leopard Trek and Farrar's withdrawals were totally understandable, ney commendable, but the peloton owes it to Weylandt to continue racing in a way that he would have encouraged. Bravo.
190km - The sun is shining at the start in Piombino with temperatures hitting 24 degrees. With no rain forecast, there will be no repeat of last year's stage over the white roads to Montalcino, which saw the riders covered in sludge in a stage eventually won by then world champion Cadel Evans. Full weather report for Piombino
191km - And they're off! The show goes on in the 94th edition of the Giro after the terribly sad circumstances of the last two days. Britain's David Millar (Garmin-Cervelo) is in the pink jersey, but expect there to be some changes in the GC today with those tricky climbs over the 'strade bianchi' and the uphill finish in the ancient Roman hilltop town of Orvieto.
11:30 - You will all heard, of course, of the news that team Leopard Trek have pulled out of the race following the shocking death of their rider Wouter Weylandt on Monday. American Tyler Farrar, one of Weylandt's best friends, has also withdrawn, as expected. The Garmin-Cervelo rider finished yesterday's tribute stage alongside Weylandt's team-mates at the finish in Livorno yesterday. There are now 197 riders remaining in the race.
11:25 - Welcome to live coverage of stage five of the Giro d'Italia, an undulating 191-kilometre ride from Piombino to Orvieto featuring the famous chalk white roads which last year, in heavy rain, so memorably turned to sludge.