Justin Bieber and Ariana Grande have confirmed that they've got a duet in the pipeline.

The pop stars revealed their collaboration in an exchange on social media website Instagram.

Biebs posted a snap of the pair of them in the studio together, writing: "congrats @arianagrande on your number 1 song. #arianabieberduet ??"

While his mildly cryptic message alone couldn't be considered as proof, Grande responded by writing: "thank u justin!! secrets out now."

And the speaker above them in the Instagram snap appears to be delighted at the news.

But fans shouldn't put two and two together and make five, because Ariana's recent activity suggests that her association with Biebs is purely professional.

She was spotted snogging her ex-BF Jai Brookes backstage at an awards ceremony last week.