Stage 18: Cahors to Angouleme (211km)
ACTION AS IT HAPPENED (ALL TIMES BST)
1658: Cadel Evans (8'34) has managed to shave three seconds off Alberto Contador's (8'37) lead in the race for the yellow jersey.
1655: Tom Boonen strengthens his hold on the green jersey by edging out Robert Hunter for fifth place as they come home 8'34 behind the leaders.
1647: Just rewards for Casar, who came off his bike early on after a crash when a dog caused a crash ahead of him, but he did brilliantly to catch up with the breakaway group and led them home in style.
1645: Yes he has. Brilliant finishing from Casar, who tastes victory ahead of Merckx, Lefevre and Boogerd.
1 Sandy Casar - 5h13¿31
2 Axel Merckx - same time
3 Laurent Lefevre - same time
4 Michael Boogerd - same time
1645: They've caught him but has Casar left enough in the tank to hold them off in the race for the line?
1643: Boogerd leads the chasers and they have clawed back a bit on Casar but with 1.5km to go they are running out of time.
1641: Casar is off with 2.5km left and it seems to take the others by surprise. He's opened up a healthy lead.
1638: Laurent Lefevre makes his move and looks strong but the other three haven't come this far to give up now. We're in for a fantastic final 5km and the longer it goes on the more it looks like it might be Casar's race.
1635: Merckx is looking for his first ever stage win in the Tour de France. The son of the legendary Eddie Merckx, who won 34 stages and five Tours, once won a stage of the Giro d'Italia, but this is the one he really wants. The pair would join a select list of father and son teams to have won a stage on Le Tour.
1633: Boogerd ups the pace a bit to see what the others are made of. It's getting a bit tasty but there is nothing separating the frontrunners, although Merckx looks comfortable.
1631: Casar appears to be the favourite to win this race if it comes down to a spring for the line. But we are getting to the stage where the other three might decide to go for it.
1623: The last sprint of the stage sees Sandy Casar take the win:
1 Sandy Casar 6pts/6"
2 Axel Merckx 4pts/4"
3 Michael Boogerd 2pts/2"
1619: The lead is being reigned in by the Euskaltel team as they look to protect Mikel Astarloza's top 10 position. It is down to less than 12 minutes now.
1613: A bit of tyre trouble for Boogerd as he gets a front puncture. He falls behind the other three but they hang back and wait for him to catch up after a quick change - a lovely touch by his three amigos.
1610: After a pretty uneventful stage we might be getting set for a decent finish. The front four will all be keen to snatch that stage win, in particular Boogerd and Merckx are in their last Tour de France and will be hoping to go out with a bit of glory.
1601: The peleton are making a bit of a move, led by the Euskaltel team who have moved ahead of the Discovery boys are they did much of the stage's donkeywork. The lead is down below 16 minutes.
1549: With 37km to go there is the first real hint that the leaders are slipping. Their advantage has slipped to 16'57.
1543: The riders have been going for over four hours now and we have just had a statistic come in that says they have been going 37.8km/h for the past hour. I struggle to get anywhere near that on the downhill stretch in Richmond Park with a following wind.
1534: The leaders just pass a fisherman sat peacefully on a chair in the middle of a lake. It's been one of those days on the Tour.
1529: The leaders now have less than 50km to go and there is still no sign of any attempts by the peloton to reel any of that time in. The difference has remained around 17'30 and Boogerd has almost made up the time difference between him and Alejandro Valverde in sixth place.
1507: The peloton are almost 17-and-a-half minutes behind and I think it is safe to say that the front four will be battling it out for the stage. It looks unlikely there will be any major moves in the race for the yellow jersey. Instead the two likely challengers to Alberto Contador - Cadel Evans and Levi Leipheimer - will probably have to make their move in the time trial on Saturday.
1503: Boogerd gets a bit of attention from the medical staff. It doesn't look too serious as he gets a bit of spray up the jersey - perhaps one of those pesky insects had a little nibble.
1456: The lead is heading towards 17 minutes with the front group now less than 70km from the finish line.
1445: Poor old Sandy Casar is clearly struggling from that early fall. He gets some attention from the medical staff - hopefully the magic spray will sort him out.
1442: After Rasmussen was thrown out of the Tour, Rabobank team captain Boogerd said: "I don't know what I should think of all this. I want to go home immediately."
His team must be glad he stuck around as he is reeling in the men ahead of him - if they can maintain their advantage over the peloton he is looking at moving up to seventh place in the overall standings.
1437: As the leaders head towards a lead of 16 minutes this is all good news for Michael Boogerd and the Rabobank team in particular.
1429: The front four are now steadily extending their lead over the chasing peloton. It is over 15 minutes now and rising.
1420: Back in the peloton and the Discovery boys, who have a comfortable lead in the battle for top team, are heading the pack.
1417: Less than 100km from the finish line and there is no suggestions that the leaders are slowing. In fact they have just edged their advantage to 14'30 - the biggest of the day.
1413: Bouygues Telecom rider Jerome Pineau has called in the race doctor. The Frenchman made an early attempt at a breakaway but could not sustain his challenge.
1407: Speaking of bare flesh, Sandy Casar is showing a rather nasty looking bloody gash on his backside as a result of his earlier fall when a dog ran in front of Frederick Willems. You would have thought they'd cover him up. I wonder if a Tour de France competitor has ever been thrown out for indecent exposure.
1356: It is a baking hot day in France - with plenty of bare chests among the fans littering the streets. All men by the way, before you lot get too carried away.
1352: The peloton make their way through the feeding area and there appears to be little sign of anyone attempting to try and catch the four leaders.
1341: It's feeding time for the leaders as they hit the 87km mark holding a lead of over 14 minutes. I think I'll have a bite myself - cream cheese and salami on a bloomer sounds the order of the day.
1326: We've just passed 70km and the peloton are over 12 minutes behind our fantastic front four. Boogerd takes the win in our fourth and final climb:
1 Michael Boogerd 3pts
2 Sandy Casar 2pts
3 Laurent Lefevre 1pt
1309: The first sprint of the day is won by Merckx:
1 Axel Merckx 6pts/6"
2 Laurent Lefevre 4pts/4"
3 Michael Boogerd 2pts/2"
1304: The leading pack are nw over 10 minutes ahead of the peloton as they pass the 65km mark.
1300: The talk on 606 is all about Le Tour's drug issues and the rights and wrongs of Rasmussen's expulsion. If you want to know more about the big story from this year's race, check out BBC Sport's guide to the controversy.
1253: The front four are staying strong - it looks like their lead ahead of the peloton is over eight minutes now.
1242: Not much movement at present as the front four are maintaining their seven-minute lead over the peloton.
1231: Casar and Merckx catch Boogerd and Lefevre and we have a front four again - over seven minutes clear of the peloton. Lefevre takes maximum points from the third climb:
1 Laurent Lefevre 3pts
2 Michael Boogerd 2pt
3 Sandy Casar 1pt
1225: Casar has a new bike after his other one got a bit dog-ged down and he is making a good attempt to catch the leaders alongside Merckx. No sign of Willems, I think he must have slipped back into the peloton.
1218: A bit of drama as Willems has a collision with a stary dog and he and Casar hit the tarmac. What is it with dogs and the Tour this year? It's ruff, sorry rough, luck on the two riders and it leaves Boogerd and Lefevre out in front on their own.
1212: The front four of Lefevre, Boogerd, Casar and Willems have extended their lead over the peloton to two minutes, but Axel Merckx is making a single-handed attempt to catch them.
1208: Lefevre takes first place in the second climb of the day:
1 Laurent Lefevre 3pts
2 Michael Boogerd (RAB) 2pts
3 Sandy Casar 1pt
1202: Boogerd and Lefevre have joined Willems and Casar in a breakaway pack as they try and edge clear of the peloton.
1155: Frederick Willems catches the two Frenchmen to win the first climb:
1 Frederick Willems 3pts
2 Jerome Pineau 2pts
3 Sandy Casar 1pt
1147: The riders are approaching the 14km mark and after failing with an earlier attempt to get away from the peloton, Jerome Pineau has started to edge clear along with Sandy Casar.
1133: Meanwhile, Michael Rasmussen has vowed to continue riding despite being thrown out of the Tour.
1131: Three-time champion Greg LeMond has also had his say, claiming that there should be no awarding of the yellow jersey this year.
1125: As stage 18 gets under way the fallout from the drugs drama that has again marred the Tour continues. Britain's Bradley Wiggins, who was forced out of the race after his team-mate Cristian Moreni tested positive for testosterone, claims the Tour has lost all credibility.
1116: The riders are off and running as they get off to a leisurely start.
1113 BST: The riders are getting ready to go for stage 18 of the Tour. It's a lengthy one at 211km - or 131 miles in old money. There are four category 4 climbs and a couple of sprints to battle for today.
Discovery rider Alberto Contador will slip on the yellow jersey for
stage 18 of the Tour de France.
The Spaniard, who inherited the lead after Michael Rasmussen was thrown out by his Rabobank team, is just under two minutes clear of nearest challenger Cadel Evans.
On Thursday, Italian Daniele Bennati won stage 17 with a sprint victory in Castelsarrasin.
Quick Step's Tom Boonen led the peloton home to reinforce his grip on the green jersey.