Justin Bieber's second single from 'Under the Mistletoe' is 'The Christmas Song (Chestnuts Roasting on an Open Fire)' and for this holiday jam, the teen recruited his mentor Usher in order to give this Christmas season standard an R&B touch. The song will warm up even the snowiest, chilliest and iciest of holiday celebrations. That's because the Biebs and Usher infuse the song with silky smooth R&B heat, harmonizing over a loose beat.

There's a bluesy guitar riff that asserts itself mid-song and The Biebs and Ush play with the melody, so the song has a super contemporary (not to mention cozy) feel as it builds up to the final chorus. Their vocal interplay is quiet complimentary -- excellent, even -- and they manage to add a modern twinkle to a Christmas classic. It's all that dreamy harmonizing, we tell ya!

Say what you will about The Biebs, but the kid can sing and he handles festive, seasonal music with his signature Bieber-ness. Everything he does sounds good and for this song, Usher brings out the best in him.

So when you're opening presents by a crackling fire this December and sipping mint-spiked hot cocoa, turn this up. It's definitely not your parents' or your grandparents' Christmas Carols. A song you've heard a dozen times has been redone for a new generation. Who knew The Biebs could be such a cultural crusader!

Listen to Justin Bieber 'The Christmas Song (Chesnuts Roasting on an Open Fire)' Feat. Usher