A couple of contenders have lost crucial seconds on stage six of the Tour de France

Last year's third place finisher Romain Bardet has finished 31 seconds behind stage winner Dan Martin after swapping bikes with a team-mate following a mechanical problem.

Defending Giro d'Italia champion Tom Dumoulin has suffered a puncture five kilometres from the finish and ended 53 seconds behind Martin.

Fellow contenders Richie Porte and Vincenzo Nibali finished three seconds off the pace, with defending champion Chris Froome five seconds further back.

Belgian Greg van Avermaet has retained the leader's yellow jersey.