Mariah Carey and Justin Bieber set "X Factor" date

Mariah Carey and little Justin Bieber are set to perform on "X Factor". Their December 15th performance will be of their new duet on Mariah's classic hit, "All I Want for Christmas Is You". Carey wrote the song and released it 17 years ago, in November 1994. (Wait! November 1994 was seventeen years ago?) Since then, "All I Want" has become a Christmas perennial. This year she re-recorded it with Justin Bieber, who sings back up in his new low register. He isn't Perry Como or even Steven Tyler, but the keeps up with Miss 8 Octaves and doesn't do too badly. Carey has said she will make a number of appearances on "X Factor" this season, largely because it's controlled by her record company, Universal Music. Also, her former and future label chief, L.A. Reid, a is a judge. This is complicated because her unofficial manager and music director Randy Jackson is a judge and mainstay of "American Idol". At any rate, set your DVRs to see the newly slimmed down Mariah sex up Justin on live TV. Let's hope there's no wardrobe malfunction. (Showbiz411)