Ariana Grande stuns the AMAs with jazzy (partly) acoustic performance

Taylor Swift may have turned up the heat with a pyro-tastic performance at the 2014 American Music Awards, but Ariana Grande blew the crowd away with a special, stripped-down medley of her latest hits.

The lights came up on a stunningly beautiful Ariana Grande wearing one of the classiest sheer black-lace gowns we've ever seen, and suddenly we were serenaded by acoustic jazz versions of her songs "Problems" and "Break Free."

PHOTOS: 21 Red-Hot Looks For Ariana Grande's 21st Birthday

Showing off the power of her vocal range while still managing to look classically gorgeous, Ariana, 21, seemed to be on a mission to prove that she's an adult, and can look good in styles other than mini-skirts and pony-tails

After the slow, melodic accompaniment of the piano and saxophone, the medley transitioned into "Love Me Harder" and the acoustic performance dropped away in favor of more modern spectacle for her duet with The Weeknd. (It still rocked!)

VIDEO: Ariana Grande Goes Galactic Glam In Awesome Sci-Fi 'Break Free' Video

The performance solidifies Grande's super star status, proving that she has the raw talent to hang with classic songstresses and lounge singers of yesteryear - plus the flair to dominate the pop landscape she's excelled with this past year.

If nothing else, it was a far cry from her Forbidden Planet-themed sci-fi spectacular that was her MTV EMA's medley earlier this month.

Earlier this year, Ariana had been battling rumors that she's a "diva" and that she's hard to work with. Check out the video below to hear how the "Problem" singer responds to these claims.