Peter Sagan of Slovakia won the third stage of the Tour de France, easing home in the final 100 metres of a 197 kilometre ride from Orchies to Boulogne-sur-Mer.

It was the Liquigas rider's second stage win having triumphed in Sunday's first full stage.

Fabian Cancellara of Switzerland retained the overall leader's yellow jersey.

Ireland's Nicolas Roche finished in the main pack, in seventh place, just one second behind Sagan. Roche is 20th overall, 25 seconds behind Cancellara.

Daniel Martin, meanwhile, had a disappointing day in the saddle. Martin lost contact with the peloton late in the stage as he got caught behind a crash and crossed the line in 105th position, 5 minutes 5 seconds behind Sagan. Martin is now 87th overall.

It was the tour's first appearance in France this year following the prologue and two stages across the border in southern Belgium, there were a number of crashes and incidents.

Yellow jersey contenders Team Sky were the first to suffer a setback when Kanstantsin Sivtsov was forced to retire.

Sivtsov, one of Sky's support riders for race favourite Bradley Wiggins, was one of several riders caught up in a crash just after the Cote de l'Eperche around 140 km into the race.

The Belarusian sat on the ground and waited for medical advice, apparently complaining of a sore knee, before his retirement was announced minutes later.

He became the first of the 198-strong peloton to withdraw from this year's race, which ends in Paris on 22 July, but he was not alone with more coming shortly after.

Other riders to be caught up in the spill were American sprinter Tyler Farrar (Garmin) and Spaniard Pablo Urtasun (Euskaltel).

The crash, which happened on a tight road, left many riders scrambling over the grass verges with their bike in a bid to get moving.

Farrar was eventually paced back to the peloton, which at that point had a 3:55 deficit on a four-man breakaway group.

The third stage had been feared by a number of different teams and riders due to a succession of six small climbs, five of which came in the last 35km, on tight roads leading to the finish line.

And those fears were confirmed when another crash on the next climb, the Mont Violette, prompted the withdrawal of Spanish sprinter Jose Joaquin Rojas (Movistar), who finished second in the green jersey points competition in 2011.

The 22-year-old Sagan eventually won a tight finish up a final rise, edging ahead of Norway's Edvald Boasson Hagen and another Slovakian Peter Velits. Cancellera was fourth with last year's tour winner Cadel Evans of Australia in sixth place.