Two of pop music's biggest names are teaming up for an as-yet-undisclosed project.

Justin Bieber and Ariana Grande have teased a collaboration that is set to be announced at 5pm GMT today.

Although the pair - who share a manager in Scooter Braun - played live together when Bieber made an appearance during Grande's Coachella headline set last year, they have not yet joined forces on record, apart from a remix of Bieber's song 'What Do You Mean?'

Some fans have speculated that they may be collaborating on a live concert rather than a song.

View this post on Instagram

👀 10 am pst tomorrow

A post shared by Justin Bieber (@justinbieber) on

Needless to say, fans are already excited by the prospect... at least, some of them. It seems that Bieber's fans are a lot more enthusiastic than the Arianators...