Team Sky's Edvald Boasson Hagen of Norway won the 17th stage of the Tour de France earlier this afternoon, the first of three days in the Alps, while Thomas Voeckler retained the yellow jersey but lost time after riding off course on the final descent.

Defending champion Alberto Contador made repeated attempts to get away from his rivals, but was caught on each occasion. He finished in the same time as Cadel Evans, the Schleck brothers and Samuel Sanchez. Voeckler lost 27 seconds and is 1 minute, 18 seconds ahead of Evans. 2010 Giro d'Italia champion Ivan Basso also lost time.

Boasson Hagen completed the 179 kilometers (111 miles) across the Alps from Gap to the Italian town of Pinerolo in 4 hours, 18 minutes. Bauke Mollema of the Netherlands was second, 40 seconds back, with Sandy Casar of France winning the sprint for third.

Voeckler veered off the course at one point during the last descent, but didn't crash.

"It's a pity, because I saw that Contador, Evans and the Schlecks finished together. If I'd taken fewer risks, I would have finished with them," he said.

Contador was not downhearted by his failure to get away.

"I felt good, and you've got to try," he said. He didn't want to talk about the stages to come.

It was the second victory for Boasson Hagen and the fourth for Norway in this year's race.

"It was very difficult yesterday, and today I was able to do better," Boasson Hagen said and continued "I felt I was capable of attacking on the last climb." Boasson Hagen smilingly added "I didn't want to lose the stage again today."

Mollema was second after Frenchman Jonathan Hivert crashed on the perilous final descent of the Pramartino. Hivert got back on his bike and came in ninth.

Voeckler had several near misses as he tried to attack during the last descent. He lost time but didn't crash.

Boasson Hagen praised the large contingent of Norwegian fans that has been supporting him and Hushovd throughout the race.

"It's really great to see all the Norwegian flags and Norwegian people around the course. It gives some extra power."

Team BMC Racing's Evans becomes more of a favorite for the title with every day he keeps his advantage of nearly two minutes over Contador.

"With shadows and stuff it was real hard to see. Voeckler ran off the road in front of me -- twice I think. It makes you take things more cautiously. You don't ever want to lose time to anyone," the Australian said and added "I've got a good advantage over Alberto now, but Alberto has shown in years gone by what he can do when he's really at his top."

Britain's Mark Cavendish came in 166th of the 169 finishers, more than 14 minutes behind Boasson Hagen, but still held on to the green jersey for the best sprinter after four victories in the flat stages. Six of his HTC-HighRoad teammates nursed him through to the end.

Thursday's second of the three Alpine stages contains three climbs that are so steep they aren't even given a category. It ends with the 14.2-mile climb of the famed Col du Galibier. The full stage is 125 miles, starting at Pinerolo.

Outside the racing Wednesday, Russian team Katusha confirmed that rider Alexandr Kolobnev's backup sample tested positive for a banned masking agent.

Kolobnev became the first rider in this year's Tour to fail a doping control when his urine sample taken after the fifth stage had traces of hydrochlorothiazide, a diuretic that can hide the presence of other drugs.

Kolobnev was in 69th place when he left the race before the 10th stage.

Katusha said Kolobnev is suspended until the Russian Cycling Federation holds a disciplinary hearing. He faces a two-year suspension.

Kolobnev was given the bronze medal in the 2008 Beijing Olympics road race after the original bronze medalist, Davide Rebellin of Italy, was found guilty of doping.