AceShowbiz -

Ariana Grande's duet with Justin Bieber is currently underway. The Nickelodeon star revealed that she'd collaborated with Bieber after the Canadian singer congratulated her on her chart-topping new single "Problem".

"Congrats @arianagrande on your number 1 song. #arianabieberduet ??" Bieber wrote on Instagram on Thursday, May 1, captioning a picture of him and Grande hanging out in a recording studio together.

Grande then replied on Twitter, "Thank u justin!! secrets out now." The two stars' collaboration has also been confirmed by their shared manager Scooter Braun. The manager posted the same photo on his Instagram page and wrote, "Always expect the unexpected. Home team. @justinbieber @arianagrande wow!!!!"

There's still no word on the title of their collaboration or when it will be released.

Grande is currently promoting her "Problem", which features verses from Iggy Azalea. The song, released in late April as the lead single off her sophomore album, has topped the iTunes charts in more than 30 countries. The track has also been predicted to make its debut within the top 10 on next week's Billboard Hot 100.