Mariah Carey sang a festive duet with her mother on a special Christmas TV show last night (14.12.10).

The pregnant star - who was hosting 'Mariah Carey: Merry Christmas To You' for US channel ABC at Los Angeles' Orpheum Theatre - invited her mother Patricia Carey to join her on stage for a rendition of festive classic 'O Come All Ye Faithful'.

Mariah explained the song - which features on her new album 'Merry Christmas II You' - is "very close" to the pair's hearts.

She said: "Please give a big hand to my very special guest. My mother, Patricia Carey, is here tonight. We're going to do a song from the new album 'Merry Christmas II You'. This is something that's very close to both of our hearts.'

However, instead of assuming her usual place in the limelight, Mariah was happy to take a backseat and allow her mother to sing lead vocals on the track, before going on to perform another duet with 'American Idol' judge Randy Jackson later in the evening.