Just weeks after she paired up with billionaire James Packer in love, Mariah Carey has announced another surprising partner in music.

The 45-year-old has posted a photo on Instagram of herself in the studio with US rapper French Montana, music producer Noel Fisher and a miserable looking 21-year-old - Justin Bieber.

The picture was captioned with the hashtag #comingsoon.

#comingsoon @frenchmontana @ehudmusic @joeyarbagey @justinbieber

A photo posted by Mariah Carey (@mariahcarey) on

Bieber is currently working on his music comeback since a slew of legal troubles threatened to derail his music career, and has admitted the pressure is taking its toil on his mental health.

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"I've been working a lot in the studio, just trying to have a consistent sound, a cohesive sound. I get in my head a lot and I get kind of depressed because I want it to work so badly," he told Ryan Seacrest on his KIIS-FM US radio show last week.

"I want people to love it. I want to inspire people. Sometimes I wonder, 'Is this good enough? Is this the direction I want to go?' I had kind of a rough week last week. I get in my head and I don't want to get out of bed sometimes." Carey, who has enjoyed many collaborations with the likes of Whitney Houston, Missy Elliot and Usher, is flying high, meanwhile. Not only is she in the honeymoon period of her new relationship with the Australian, she will on Wednesday receive her star on the Hollywood Walk of Fame.

It is unclear whether Packer will attend Wednesday's ceremony.

- AAP