Despite the victory, however, the squad failed to put its overall hope Tejay van Garderen in the yellow jersey of race leader, after Team Sky and Chris Froome finished just one second down on the American team.
Froome could be seen taking large turns at the front for Sky as they matched BMC pedal stroke for pedal stroke over the hilly 28 kilometre route from Vannes to Plumelec.
Only on the dragging final climb to the finish line did Sky appear to falter, with Nicolas Roche dropping slightly off the pace and Froome dropping back to pace him on the last few hundred metres.
The Movistar squad of Colombian GC hope Nairo Quintana also did well, finishing in third place just four seconds off the pace of BMC.
Tinkoff-Saxo and Astana fared less well, however, with Alberto Contador and Vincenzo Nibali conceding time to van Garderen, Froome and Quintana.
Froome now leads van Garderen by 12 seconds overall, with Greg Van Avermaet (BMC) in third at 27 seconds. Contador is fifth at 1-03, Quintana ninth at 1-59 and Nibali is 13th at 2-22.
The riders will now enjoy a rest day in Pau on Monday before the race heads into the Pyrenees and then the Alps. Even after nine days, the race is still wide open going into the second week.