Rose Byrne, P. Diddy and Elisabeth Moss Head to 'Greek'

The cast ensemble of "Get Him to the Greek" has expanded with the addition of Rose Byrne, Sean "P. Diddy" Combs and Elisabeth Moss. The trio has been signed to star alongside Jonah Hill and Russell Brand in the spin-off movie based on Brand's character Aldous Snow from "Forgetting Sarah Marshall".

While rapper/actor Diddy will play record company executive Sergio, "Mad Men" actress Moss will take on Daphne Binks, the uptight girlfriend of Hill's character. "Damages" star Byrne, on the other hand, is going to fill the role that Emily Blunt was originally rumored to be cast in. She will portray a promiscuous pop musician named Jackie Q who happens to be the former girlfriend of Snow.

"Get Him to the Greek" is a Universal Pictures comedy to be directed by "Forgetting Sarah Marshall" helmer Nicholas Stoller. It follows a fresh-out-of-college record-company intern who is hired to get an out-of-control rock star Aldous Snow from London to a gig at Los Angeles' Greek Theatre. While performing his job, he is introduced to an out-of-control life of hookers and blow.

Words are, musicians Katy Perry, Christina Aguilera, Pink and Dee Snider could take part on the feature project in addition to the existing cast ensemble. The Judd Apatow-produced movie reportedly will start shooting in the fall for a 2010 release.