Nathan Fillion has claimed the lead role in Drive, the mid-season Fox drama chronicling an underground race across America and exec-produced by former Firefly boss Tim Minear. Fillion, who initially passed on the gig last spring (due to a scheduling conflict), takes over for Ivan Sergei, who played Alex Tully, a charming, rogue landscaper searching for his abducted wife, in the original pilot. In other casting news, courtesy of the Ausiello Report: Happy Days' Marion Ross will swing by Brothers & Sisters in February, playing Sally Field's mother, and Dancing with the Stars alumna Stacy Kiebler has booked a multi-episode arc on What About Brian, playing a super-leggy roadblock for Bri and Bridget.