Dwayne Johnson stuns fans with a gritty transformation as UFC champ Mark Kerr in 'The Smashing Machine' trailer.

Dwayne Johnson stars as former wrestler and UFC star Mark Kerr in a new trailer for Benny Safdie's "The Smashing Machine."

In the footage, which you can watch above, Dwayne Johnson looks unrecognizable as MMA fighter and two-time UFC Heavyweight Tournament Champion Mark Kerr. We see Kerr in multiple fights, as well as talking about his ethos towards the sport. Johnson, of course, started out as a professional wrestler, so this seems like a role that was made for him.