Tour de France 2010
Start: 3 July, Rotterdam Finish: 25 July, Paris
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Contador will be aiming to hold on to his slender lead with five stages remaining
Alberto Contador took advantage of Andy Schleck's misfortune on the 15th stage of the Tour de France to take the overall lead from his nearest rival.
Schleck, attempting to attack the defending champion near the summit of the final climb of the day, saw his chain jump off and jam his rear wheel.
Contador seized the chance to strike and overturned a 31-second deficit to finish with an eight-second lead.
But Schleck claimed it was against the race's etiquette to profit in this way.
"My stomach is full of anger," said Schleck.
Frenchman Thomas Voeckler won the stage between Pamiers to Bagneres-de-Luchon.
It was France's fifth stage win of this year's Tour, and the first time since 2004 the hosts have won successive stages, after Christophe Riblon's victory on Sunday's 14th stage.
But the real drama of the day, that could yet decide the winner of the Tour, took place amongst the race leaders as they neared the top of the Port de Bales, on the second day in the Pyrenees.
And afterwards, Schleck was furious with Contador for having taken advantage of his mechanical failure.
For sure these guys don't get the fair play prize today
"The race is not finished and I want to take my revenge. I can end it like a champion."
The 25-year-old, who will on Tuesday wear the white jersey for best young rider, was among a swathe of riders who crashed on the second stage from Brussels to Spa, when the peloton controversially waited.
He added: "These guys waited in Spa when I crashed, so that was fair. Today is a different story.
"I would not have raced like that and taken advantage of that situation. For sure these guys don't get the fair play prize today."
Contador, who waited for Schleck when he crashed in the second stage to Spa, said he did not see the incident.
"I was told there was an incident but when I attacked I was not aware of it," the 27-year-old told reporters.
"I planned to attack anyway, and when I knew what had happened to him [Schleck] I was already ahead and racing," he said.
"Of course I know it's a delicate situation and could lead to debate, but I don't believe that to lose or win 30 seconds at this point will make you win or lose the Tour de France."
The stage had started at a fast pace, the peloton quickly clamping down on a series of attempted breakaways, until a group of 10 riders - including eventual winner Voeckler - got away after the feed station at 90km.
The group stretched their advantage to more than 10 minutes over the climbs of the Col de Portet d'Aspet and the Col des Ares and onto the foot of the final, hors category, Port de Bales.
I was told there was an incident but when I attacked I was not aware of it
The pattern appeared to be set and, despite Schleck's team, Saxo Bank, doing all of the work on the front of the peloton, there was little to suggest the controversy to come.
As the break's lead gradually dropped to the six-minute mark, Voeckler saw his chance on one of the steeper sections and set off on a lone attack.
Behind, Schleck tested the legs of his rivals as the chasing bunch became smaller and smaller, but was unable to get away, and another game of cat and mouse amongst the favourites seemed to be the order of the day.
However, as Voeckler neared the summit some four minutes ahead, Schleck caught Contador napping, and pounced.
The Luxembourger quickly opened up a 20-metre gap, but before he had a chance to press home the advantage, his chain slipped, jamming his rear wheel.
Cycling etiquette says that riders should not attack the yellow jersey wearer when he falls or suffers a mechanical problem.
Astana's Alexandre Vinokourov, the first to respond, appeared to ride past Schleck at tempo rather than attacking.
But his team-mate Contador sprang from the bunch and powered ahead, followed by Samuel Sanchez and Denis Menchov, leaving Schleck to dismount and wrestle with his chain.
Schleck fought back bravely up the remaining section of the mountain to try to close the gap, but Contador, with Sanchez and Menchov, raced down the descent to Bagneres-de-Luchon to take the overall lead.
Britain's Bradley Wiggins had another disappointing day, finishing 9'35" back, and has now dropped to 23rd place overall, 17'44" behind.
As at the start of stage 15, Team Sky's highest-placed rider remains Sweden's Thomas Lovkvist.
Stage 15 results:
1. Thomas Voeckler (Fra/Bbox-Bouygues) 4h 44 min 52 sec
2. Alessandro Ballan (Italy/BMC Racing) ) +1'20"
3. Aitor Perez (Spain/Footon) same time
4. Lloyd Mondory (France / AG2R) +2:50"
5. Luke Roberts (Australia / Milram) same time
6. Francesco Reda (Italy / Quick-Step) same time
7. Alberto Contador (Spain / Astana) same time
8. Samuel Sanchez (Spain / Euskaltel) same time
9. Denis Menchov (Russia / Rabobank) same time
10. Brian Vandborg (Denmark / Liquigas) same time
1. Alberto Contador (Spa/Astana) 72hrs 50mins 40secs"
2. Andy Schleck (Luxembourg/Saxo Bank) +8"
3. Samuel Sanchez (Spain/Euskaltel) +2'00
4. Denis Menchov (Rus/ Rabobank)+2'13"
5. Jurgen Van den Broeck (Bel / Omega Pharma-Lotto) +3'39"
6. Robert Gesink (Ned / Rabobank) +5'01"
7. Levi Leipheimer (US / RadioShack) +5'25"
8. Joaquin Oliver Rodriguez (Spa/ Katusha) +5'45"
9. Alexandre Vinokourov (Kaz / Astana) +7'12"
10. Ryder Hesjedal (Can / Garmin) +7'51"
16. Thomas Lovkvist (Swe/ Sky) +12'09"
17. Nicolas Roche (Ire/ AG2R) +12'34"
22. Cadel Evans (Aus/ BMC) +16'16"
23. Bradley Wiggins (GB / Sky) +17'44"
31. Lance Armstrong (US / Radioshack) +40'31"
72. Geraint Thomas (GB / Sky) +1h 33'12"
149. Stephen Cummings (GB / Sky) +2h 47'18"
151. Mark Cavendish (GB / HTC-Columbia) +2h 49'43"
157. David Millar (GB / Garmin) +2h 57'19"
163. Daniel Lloyd (GB / Cervelo) +2h 59'45"
166. Jeremy Hunt (GB / Cervelo) +3h 01'58"