Justin Bieber and Chris Brown are no strangers to hit records, nor each other. The two singers have collaborated twice; once on a remix to the Biebs' "Up" from Never Say Never: The Remixes and, more recently, on C. Breezy's latest single from F.A.M.E., "Next 2 You." Now, rumor has it that the duo is back in the studio again. 

Justin and Chris met up at the Record Plant in Hollywood on Monday, July 18. There are no details yet as to what the pop stars were working on, but it's been speculated that they were hard at work on Bieber's new album, said to have an "edgier, mature" sound.