BMC, led by one of the race favourites in American Tejay Van Garderen, edged out Etixx-Quick Step by two seconds on the 22.7km course around Lido Di Camaiore. FDJ were third at nine seconds.
The Astana team of Italian Vincenzo Nibali, the winner in 2012 and 2013, finished sixth at 15sec.
Nibali is likely to face stiff competition from FDJ's Thibaut Pinot and Spaniard Alejandro Valverde, the Movistar team-mate of last year's champion, Nairo Quintana.
Movistar were 10th at 29sec.
Oss will wear the leader's blue jersey on Thursday's 207km second stage from Camaiore to Pomarance.