04/15/2009 at 08:10 PM EDT
's Elisabeth Moss is temporarily leaving the Sterling Cooper ad agency in N.Y.C. to join Sean "Diddy" Combs in the spin-off to the comedy Forgetting Sarah Marshall
The actress, 26, and Diddy
will star alongside Jonah Hill and Russell Brand in the upcoming Judd Apatow film Get Him to the Greek
In the film, Moss will play Daphne Binks, the girlfriend of Hill's character (Aaron Greenberg), who gets tempted by an out-of-control, self destructive rockstar (Aldous Snow) played by Brand. Combs plays the role of "Sergio," the owner of the record label. The film follows Greenberg who's hired by a record company to accompany Snow from London to a concert at the Greek Theatre.
Moss, who got engaged
's Fred Armisen in January, plans to film the movie at the same time as Mad Men