Cyril Dessel's masterly descent of the Col de la Bonette-Restefond clinched the prestigious 16th stage of the Tour de France from Cuneo to Jausiers.
The Ag2r-La Mondiale rider broke away from the leading group alongside Sandy Casar, Yaroslav Popovych and David Arroyo, who descended together from the highest peak in Tour history.
Dessel made his move 800m from the finish, and held his lead through a final right-hander 80m from the finish to take his first stage win in a Grand Tour, ahead of Casar, Popovych and Arroyo.
CSC were able to maintain control of the group containing Frank Schleck, who stays in the maillot jaune for another day.
The big loser was Rabobank's Denis Menchov, who struggled on the Bonette and drops one minute 13 seconds behind the Luxembourger in the general classification.
Schleck maintains his seven-second lead on Bernhard Kohl, with Cadel Evans a further one second back.
