The UFC superstar showed off his impressive acting chops in the latest trailer for the upcoming "Road House" flick starring Jake Gyllenhaal ... perfectly embracing the antagonist role in his first major Hollywood gig.

Gyllenhaal is playing a UFC fighter-turned-bouncer in the reimagining of the '80s classic with Patrick Swayze ... and judging by the first look of the project, McGregor is gonna have a ton of screen time.

At one point in the trailer, Conor -- who's playing a badass named Knox -- enters a bar and immediately raises hell ... smashing a bunch of tables with a golf club and beating the crap out of Gyllenhaal's Elwood Dalton character.

The teaser also shares multiple flashes of different scenes involving the former champ-champ ... so it's fair to say McGregor's role ain't just a quick cameo.

Conor praised his own performance while sharing the snippet on social media Wednesday ... saying, "Fighting, acting, there’s nothing this Mac can’t do! Here’s the trailer featuring my brother, Jake Gyllenhaal, and me going toe-to-toe in the wildest action movie ever – Road House!"

"My acting debut is gonna leave a mark! Long live Knox!"

While Conor is pumped, the project is at the center of a bit of drama at the moment ... as director Doug Liman said he's boycotting its showing at the SXSW festival over the decision to not put his movie in theaters.