The first trailer for Jake Gyllenhaal's new boxing movie Southpaw has been released, check it out here.

The actor gained 15 pounds of muscle to play boxer Billy 'The Great' Hope in Antoine Fuqua's drama.

The film also stars Rachel McAdams as Billy's wife Maureen, Forest Whitaker, 50 Cent and Naomie Harris.

Southpaw is out in cinemas on July 31 - see Gyllenhaal's amazing transformation for the role by watching the trailer below.