Michelle Williams talks about pressure of portraying Marilyn Monroe (Video)

Michelle Williams had a lot of pressure on her shoulders, portraying one of Hollywood's most legendary sex symbols in "My Week with Marilyn," but thankfully the actress didn't realize that fact until after she had finished filming the movie.

"Because so many people have so many ideas about who Marilyn Monroe was and after a certain point in your research, you have to filter all the noise out and you have to pin something down and go, 'Okay, this is my Marilyn. This is the way I see her. This is the way I interpret her.' And I hope I do it justice," Williams, 31, said in an interview provided by The Weinstein Company.

"Then of course, afterwards, now that it's come out and it's something that's going to be talked about, then all of a sudden it's like, 'Oh what did I take on? She means so much to so many people!'" Williams added. "Now you feel the expectations. I didn't really feel it before."

"My Week with Marilyn" depicts the week that British writer Colin Clark, played by Eddie Redmayne, worked as Monroe's assistant while she was filming "The Prince and the Showgirl" in the United Kingdom in the summer of 1956.

"I first saw him in New York, in a play called "Red" and when I saw it, I didn't know what to make of him," Williams said of Redmayne. "I didn't know if he was American, I just assumed he was American and exactly the person that he played becau! se he wa s so brilliant and then come to find out, he's an English boy who went to Eton! Remarkably, there were some similarities between his upbringing and Colin's [Clark] upbringing, but he's incredibly versatile and what I saw him do in 'Red' is nothing like what I saw him do in this movie but his capacity and his talent in that play was incredibly overwhelming. I couldn't imagine anyone better to play this part.

Redmayne, who won a 2010 Best Featured Actor Tony Award for his role in "Red," has also appeared in films like "The Good Shepherd," "The Yellow Handkerchief," "Savage Grace," "The Other Boleyn Girl" and "Black Death."

In "My Week with Marilyn," Williams took on the appearance, speaking voice and recreated several iconic movie scenes from one of Hollywood's most famous leading ladies and sex symbols, Marilyn Monroe, who died in 1962 at age 36.

"I grew up with a picture of her in my bedroom and it was just a picture of her wearing a white dress and she's at Roxbury with Arthur Miller and she's just spinning through the trees," Williams said about Monroe.

"So my primary association with her wasn't of the icon, it wasn't of the sort of sex symbol, it was like a girl-to-girl kind of relationship that I had," the actress said. "I didn't feel like she was holding something above me, some sort of sexual power that I didn't understand, she was just sort of a girl spinning in the trees. So that was my first sort of, that was my first approach. And it was a personal approach."

Williams, who rose to fame with a supporting role on the WB series "Dawson's Creek," spent hours absorbing all things Monroe and came to her own conclusions about the actress.

"When I was first prepping to play Marilyn Monroe, what I didn't understand was the separation between her persona and who she was on the inside and what I came to realize after reading a lot about her, spending time pouring over images and films, press recordings and little video clips, was that Marilyn Monroe, how you commonly th! ink of M arilyn Monroe, that was a character."

"That was an act," she added. "A finely-honed act that she put on, that she developed over time with impact from teachers, a lot of sort of face time in the mirror, figuring out how to move in a way that accented what she had naturally. Marilyn Monroe was a character that she developed."

Williams, a Montana native, is also known for movies such as "Brokeback Mountain," which starred her then-boyfriend Heath Ledger and the R-rated "Blue Valentine." Both movies earned the actress Oscar nominations. Many critics have already cited Williams as being a front-runner the next Best Actress Oscar Award.

"[The script] read beautifully, first of all," Williams said of her decision to take on the role. "I didn't know Colin Clark, I hadn't read his books or anything, but I thought that his script has a pace and a flow and a heart. And her. I just respond to her."

Williams also recently filmed the independent movie "Take This Waltz," which was directed and written by Sarah Polley and also stars Seth Rogen and Sarah Silverman. No wide release date has been announced.

Williams is currently shooting the fantasy film "Oz: The Great and Powerful." Production began in July. Williams plays the witch Glinda, while James Franco plays the title role of the wizard. The movie also stars Mila Kunis and Rachel Weisz and is set for release on March 8, 2013.

Williams recently said in an interview with Hobo magazine that she often dreams of "quitting acting," adding: "Walking away and becoming a laundress or a sous chef or maybe writing other people's love letters for a ! living. Clearly, I don't like to be in charge. And thinking of quitting is just keeping going in disguise. When you have options, anything is bearable. It's when a situation is inescapable that it becomes hell."

Check out the trailer for "My Week with Marilyn" below.