Andy Schleck has lost his yellow jersey as overall leader of the Tour de France to defending champion Alberto Contador after suffering mechanical failure at a disastrous moment.

Schleck had accelerated less than 4 kilometres from the top of the big climb of the day, the Port de Bales, but almost immediately lost his chain, forcing him to stop on the side of the road and wait for assistance.

He then had to force his way back through the field as he attempted to catch up with Contador and the other leaders in the overall competition, but was unable to make up enough time. Contador now holds the yellow jersey by eight seconds from Schleck.

French champion Thomas Voeckler won the day's stage, the second of the Tour de France's four big stages in the Pyrenees, with a solo ride.

Schleck angrily said that according to cycling etiquette the riders should have waited for him, which was what happened when he crashed during an early stage.