Health concerns have forced Christian Bale to pull out of the lead role in director Michael Mann's Enzo Ferrari biopic.

Reports suggest the Oscar winner didn't feel he could gain the necessary weight for the role by the spring (16), when filming was scheduled to start.

Bale was cast as the legendary car manufacturer.

The star has tested his health for roles in the past, losing and/or gaining weight for The Fighter, The Machinist and American Hustle.

Sources tell The Hollywood Reporter Mann is working on recasting the part, so the film, based on Brock Yates' book Enzo Ferrari, The Man, The Cars, The Races, can begin on schedule.