Roche, who rides for the Ag2r-La Mondiale team and who is making his debut in the event this year, was one of eight riders who broke away after reaching the summit of Col-du-Petit St Bernard on the 159k stage.
The eight riders battled it out on the 10k descent, splitting into two groups of four. Roche was in the second quartet, and by the time they had caught up to the leaders, Mikel Asterloza had made the decisive burst that would see him win the stage.
Roche finished the stage in fourth place, and this is his second top 10 finish on the Tour so far. He lies in 30th place overall, 16'48" behind race leader Alberto Contador of Astana. Lance Armstrong remains in second place, 1'37" behind Contador.