Giamatti joins in Saving Mr Banks
Paul Giamatti and Jason Schwartzman are to help out in Saving Mr Banks.
The Rock Of Ages actor and the Rushmore star are the latest additions to John Lee Hancock's big-screen adaptation of PL Travers' book, Variety reports.
Tom Hanks is already on board as animator Walt Disney, while Emma Thompson is set to portray the Australian author in the movie, which tells the true story of Walt's 14-year courtship of Pamela Travers for the rights to her Mary Poppins character, which she was reluctant to sell to the studio.
Paul is tipped to play the author's chauffeur, while Jason - who recently reunited with filmmaker Wes Anderson in Moonrise Kingdom - is rumoured to portray Richard Morton Sherman, a songwriter who wrote a number of songs for Disney films including Mary Poppins.
English actress Ruth Wilson, who has been filming The Lone Ranger with Johnny Depp, has also joined the cast, and is said to be portraying the author's mother in flashbacks opposite Colin Farrell, as the author's father.
Paul, who played Tom Cruise's manager in Adam Shankman's big-screen musical Rock Of Ages, will next appear in Steve McQueen's Twelve Years A Slave with Michael Fassbender, and the Julian Fellowes-penned Romeo And Juliet remake alongside Damian Lewis and Hailee Steinfeld.