Los Angeles: Pop star Mariah Carey is the special secret guest on Justin Bieber`s Christmas album.
The 17-year-old singing star, Bieber announced via Twitter that the pair will duet on her single `All I Want For Christmas`, reported MTV online.
"Oh yeah...didnt I promise everyone I would tell them who my last special guest is on my Christmas album," he tweeted.
"I mean the fact that I might be singing with one of the greatest voices ever one of the greatest songs of Christmas ever," he added. Bieber then tweeted a link to a video of Carey.
"Well like I said…It is not your normal Christmas album. Right Mariah Carey," he wrote on Twitter. In the video, Mariah said: "What`s up I`m Mariah Carey and I`m here today to tell you a little secret. Justin and I are doing this duet together, it is my song `All I Want For Christmas`, which I wrote and produced.
"I`m very excited about it. I`m sure many people are surprised and you`re going to be more surprised when you hear it. The song sounds great and I`m very excited for you all to hear it this Christmas and be totally festive with our festive collaboration," she added.
The `Baby` singer has worked with high-profile stars on a selection of duets for the festive record - including Busta Rhymes, Boyz II Men, Usher and The Band Perry.