The film, which centers on a rarely told moment in Monroe's life as she attempts to free herself from the pressures of stardrom, also features two musical numbers where Williams gets to inhabit Monroe's show-stopping style.
"My Week With Marilyn" arrives in cinemas Nov. 23. Read the Playbill.com story here.
Tony Award-winning Anything Goes director-choreographer Kathleen Marshall and Denise Faye (Guys and Dolls, Song and Dance, Jerome Robbins' Broadway) co-choreographed the songs "Heatwave" and "The Old Black Magic" for the film.
Marshall also enlisted her Anything Goes cast member Adam Perry and Sean Vanderwilt ("Burlesque," "The Producers") as dancers to back Marilyn during "Heatwave."
The soundtrack to the film also features Williams' vocals as Monroe on "When Love Goes Wrong, Nothing Goes Right/Heatwave," "It's a Wrap, I Found a Dream" and "That Old Black Magic." Here's a look:
