(Photos: Yuzuru Sunada)

Embattled champion Alberto Contador lost more time to his key yellow jersey rivals on Thursday as Olympic champion Samuel Sanchez claimed his maiden win in the Tour de France. 

Spaniard Sanchez came over the finish line of the 211km 12th stage ahead of Belgian Jelle Vanendert after attacking the Omega-Pharma rider inside the final 400 meters of the 13.3km climb to Luz Ardiden.

Frenchman Thomas Voeckler, of Europcar, upset the form book to retain the race leader's yellow jersey after the first of three consecutive days in the Pyrenees. But on the first high mountain stage of the race, several big names dropped out of contention, with Dutchman Robert Gesink, Andreas Kloden of Germany and American Christian Vandevelde all losing time.

Arguably the biggest loser was Contador, who for the first time in the race fell victim to tactics that the Schleck brothers Andy and Frank had threatened to employ in a bid to outfox him. Contador ultimately lost over 10sec to his key rivals when he dropped off the pace late on the final climb to the Pyrenean ski station.

Frank Schleck, who had escaped from Voeckler's chase group in the final 3km, finished third, just ahead of Voeckler and fellow yellow jersey rivals Cadel Evans, Ivan Basso and his younger brother Andy.

In the overall standings Voeckler now leads Frank Schleck by 1min 49sec, with Evans third at 2:06 and Andy Schleck fourth at 2:17.

Contador, who lost over a minute to his rivals in a crash on the first stage, is now seventh overall at 4:00 behind. The Spaniard, who has been suffering from a knee injury, later tried to play down his deficit.

"I was trying just to be vigilant throughout the final climb. I saw the two brothers speaking between themselves so I knew one of them was going to attack," said Contador. "Finally it was Frank who went, he must have been the stronger of the two. "But I'm still satisfied with the first high mountain stage."

Andy Schleck, who has finished runner-up the past two years to Contador, looked a happy man at the end of the stage.

"It was a perfect day for us. It was a first test, and not the last," said the Luxemburger. "Obviously today wasn't decisive but we showed our strengths. Contador isn't unbeatable, he lost more time today."

Sanchez, who finished fourth overall last year, had been aiming for podium place this year. But after losing over a minute on the opening stage, the man from Oviedo decided his first priority would be a first stage win. After counter-attacking an earlier breakaway on the descent of the Col duTourmalet, the second of three climbs on the stage, he went on to build a lead with Vanendert before leaving the Belgian behind in the finale.

"I really wanted this stage, I was determined," said Sanchez, who gestured wildly as he crossed the finish line. "I lost a lot of time in the first week, so this has helped me make amends."