Last night on Jimmy Fallon, Mariah Carey was a guest but her performance didn't even make it to 'Late Night With Jimmy Fallon.' Before the show, Jimmy, Mariah, The Roots and a bunch of schoolkids got together to sing a stripped down performance of Mariah's holiday classic "All I Want For Christmas Is You" and that might've won Christmas in the process. Check out the exclusive internet video below.

Mariah Carey wasn't even scheduled to be a guest last night on 'Late Night' but Mimi proved herself more than game, showing up to 30 Rock for a simple backstage performance. Jimmy Fallon turned on his iPhone camera, propped it up in the corner and he and Mariah - along with the backing of The Roots on children's instruments and a chorus of school kids - belted out a rendition of "All I Want For Christmas Is You" that will melt even the most frozen Scrooge's heart.

Even at 42 years old (!!), Mariah still looks and sounds as good as she did back in 1994 when the song was originally recorded. Of course it helps to have a bunch of cute kids singing along and The Roots playing a Fisher-Price xylophone and kazoo.

Watch the video below and see if you Grinch heart grows three sizes this day.