Justin Bieber is working hard on his new album, and he's invited some friends to come along too.

Both Cody Simpson and Usher tweeted about their work with Justin this week. Who guessed it?

Usher said "Just left the studio with the lil bro...soundin good." And Cody posted "Chilled with the matem @justinbieber in the studio tonight. Look for some great records coming #AustraliaToCanada."

Which collaboration do you want to hear more?

Sources: Hollywood Life (Usher), Disney Dreaming (Cody)