If you can't spot The Rock in the first image from his latest movie set ... you ain't alone -- 'cause Dwayne Johnson looks unrecognizable in his new role as ex-UFC fighter Mark Kerr!
The WWE superstar transformed into the MMA legend for A24's upcoming project, "The Smashing Machine," and check out a pic he posted from Day One of filming ... the Brahma Bull's no longer distinguishable.
Dwayne covered up his signature tats .