Justin Bieber collaborates with Chris Brown

Singer Justin Bieber has collaborated with Chris Brown for a track dedicated to their fans.

The 20-year-old pop star posted a picture of the 'Run It' star and himself from a studio on Instagram.

"Studio, me and CB (Chris Brown) did one for the fans," he captioned the photograph.

No other details on the track have been revealed, but this is the second time that the stars are working with each other. They previously worked together for a duet on Breezy's 2011 album, FAME, called 'Next to You'.