UFC Star Demian Maia -- I'm Training with Bruce Leroy HIMSELF

WHO'S DA MASTAH??? UFC middleweight badass Demian Maia ... because his new trainer is none other than BRUCE LEROY from the 80s cult classic "The Last Dragon."

Leroy -- real name Taimak (right) -- tells TMZ, he met Maia during a recent training session in New York ... and they immediately hit it off.

According to Taimak -- an accomplished martial artist in his own right -- Maia approached him in the gym, claiming he was a big "Last Dragon" fan (who isn't?) and the two kept in touch.

Now, Taimak says he and Maia have started to train together -- prepping Maia for his upcoming UFC 148 bout against Korean badass Kim Dong-Hyun, who's lost only ONE fight in his pro career.

As for training details -- Taimak was tight-lipped, not wanting to tip off Maia's Korean competition.