The Forever hitmaker was ordered back to rehab on Friday (28Feb14) to extend a two-month anger management and drug rehab program.
Before he headed to court, he posted a picture of himself and Grande at a dance rehearsal with the caption "coming soon" on his Instagram.com page.
Grande fuelled rumours of a collaboration by sharing lyrics Brown had posted online and her manager, Scooter Braun, wrote on Twitter.com, "That was an amazing session. Excited for this incredible duet on the way."
It is likely the song's release will be postponed until Brown is released from rehab. He is due for another court hearing on 23 April (14).