Rosé and Bruno Mars brought the apateu to the Grammys -- with the duo performing a rockin' version of their hit collab, "APT.," to get the awards show underway.

The two took the stage to intro "music's biggest night" just minutes ago ... and before host Trevor Noah uttered a single joke, the vibes were set with the Billboard-topping track based on the Korean drinking game.

The BLACKPINK member rocked black pants, a white tank and a black tie for the occasion ... with Bruno electing for a matching suit and black bandana.

The song was nominated for three awards on the night -- record of the year, song of the year and best pop duo/group performance ... but already lost one to Ariana Grande and Cynthia Erivo for the "Wicked" ballad, "Defying Gravity," before the main broadcast.

They certainly weren't sore losers about it ... as the two sang and danced around the stage with a ton of energy.

The party's just getting started ... and what better way to start than by getting the crowd -- with stars like Justin Bieber, Billie Eilish, Kendrick Lamar, Chappell Roan in attendance -- in on a lil' drinking game??