Mariah joins Bieber on Christmas LP

Pop star Mariah Carey is the special secret guest on Justin Bieber's Christmas album.

Mariah Carey, who has been busy regaining her diva strength after giving birth to twins Moroccan and Monroe back in April, has confirmed that she'll be gracing us with her gifted vocals once again on a remake of her own holiday classic, 'All I Want for Christmas Is You,' sung with none other than Justin Bieber.

The duet will appear on JB's forthcoming holiday album, 'Under The Mistletoe,' which also includes collabs with Usher and Boyz II Men. Leading up to Mariah's duet announcement, Bieber had been tweet-teasing fans about a mystery singer set to appear on the CD with messages like, "Who is the living legend that I got on the album?" and "I mean the fact that I might be singing with one of the greatest voices ever one of the greatest songs of christmas ever..."

Now that they mystery is solved, a new question arises: Will the reboot of this classic Christmas song by two of music's biggest stars take the holiday favorite to a whole new level, as Mariah suggests, or leave us wishing the pop stars didn't mess with it? Find out for yourself when 'Underneath the Mistletoe' releases on November 1.