Frenchman Sylvain Calzati broke away to claim Sunday's eighth stage of the Tour de France, a 181k stretch from St Meen-le-Grand to Lorient.
The AG2R rider, whose only previous victory was the Tour de l'Avenir in 2004, sped clear from a leading group 30k from the finish and never looked back.
Finn Kjell Carlstrom finished second and Frenchman Patrice Halgand third, two minutes and five seconds behind.
Australian Robbie McEwen won the mass sprint for fourth, two minutes 15 seconds after Calzati, the last pick in his team's choice for the Tour, crossed the line.
Ukraine's Serhiy Honchar of the T-Mobile team retained the overall leader's yellow jersey after finishing in McEwen's bunch.
After a first breakaway attempt was caught by the peloton, six riders then tried their luck after the village of Plouguenast 135k from the finish.
CSC American rider David Zabriskie, German Matthias Kessler (T-Mobile), Belgian Mario Aerts (Davitamon Lotto), Calzati and Carlstrom (Liquigas) were joined by Halgand (Credit Agricole) and opened a seven-minute gap, but it was the 27-year-old Calzati who asserted in the end.
They were cheered by thousands of spectators on the Mur de Bretagne, a two-km third-category ascent in a region which is the heart of cycling in France.
Before the start, the Tour paid tribute to Louison Bobet, born in St Meen-le-Grand, who was the first man to win the race three times in a row from 1953-55.
The riders fly to Bordeaux later on Sunday before enjoying a rest day on Monday. The race resumes on Tuesday with the ninth stage, a 169.5k ride from Bordeaux to Dax, the last flat stage before the Pyrenees.
