Riders receive medical assistance after a collision during the sixth stage of the 99th Tour de France cycling race between Epernay and Metz, July 6, 2012. (REUTERS/Joel Saget)

By Gilles le Roc’h

METZ, France, July 6 (Reuters) – Peter Sagan sealed the first week of his maiden Tour de France with his third stage victory in a crash-ridden 207.5-km sixth stage which seriously hurt the chances of some leading favorites.

The 22-year-old Slovak outpaced the leading part of a scattered bunch to achieve a spectacular treble ahead of Germany’s Andre Greipel, the winner of the two previous stages and one of many riders to hit the tarmac between Epernay and Metz.

Australian Matthew Goss took third while Swiss Fabian Cancellara, who also avoided the worst pile-up of the day, retained his overall leader’s yellow jersey.

“I won five in California, four in Switzerland, now three in France. I didn’t expect to win that many stages in my first Tour but why stop now?” said Sagan, who went tumbling to the tarmac in the previous stage.

“I was lucky to be unhurt. In stages like this, everybody wants to be in the front and it causes unnecessary crashes,” he told reporters.

Some Tour contenders were not so lucky and three riders, American Tom Danielson, Italy’s Davide Vigano and Spain’s Mikel Astarloza were forced to bid farewell to the race.

World champion Mark Cavendish was held up in the chaos which took place 26 kilometers from the finish and was, therefore, unable to be part of the final sprint, but other riders have probably lost the Tour even before Saturday’s first mountain stage.

American team Garmin were among the hardest hit, losing Danielson, eighth last year, while their Canadian leader Ryder Hesjedal, escorted by David Millar and Tyler Farrar, finished more than 13 minutes off the pace.

The Giro d’Italia champion was sent to hospital for checks after crossing the line.

FIRST MOUNTAIN STAGE

“We’ll have to change our game plan now and cheer each other up. We’ll get over it,” said Garmin’s David Zabriskie, who launched the day’s long break and was caught under the last kilometer marker.

Among the other top-flight riders held up in the day’s crashes were Luxembourg’s Frank Schleck and Spain’s Alejandro Valverde, who both lost 2:09, while Dutchman Robert Gesink finished 3:31 adrift.

“”It hurts all over. It was awful. Hopefully nothing’s broken,” said Schleck, who finished third overall last year.

RadioShack rider Cancellara, who leads Briton Bradley Wiggins by seven seconds in the general classification, spent his 28th day in total in the yellow jersey but conceded it would probably be the last this Tour.

The peloton reaches the first serious climbs in the 199-km seventh stage ending at the summit of La Planche des Belles Filles.

“”Someone else will probably hold the jersey tomorrow. I will now need to recuperate from the physical and the mental stress of the jersey and concentrate on the time trials ahead,” Cancellara said.

Sagan, who is not yet a mountain specialist, will also wait for flatter days to shine again and defend his lead in the points classification.

“My goal now is to reach Paris with the green jersey. The Tour is still very long and it’s important to save some energy for the third week,” he said.