Michelle Williams Could Barely Walk in Her Tight Marilyn Monroe Costume

 Jemal Countess/Getty

Goddesses don't walk — they glide! 

As a young Marilyn Monroe in My Week with Marilyn, Michelle Williams had to squeeze her curves into very, very tight clothes — and the result, according to costar Kenneth Branagh, was otherworldly.

"Seeing Michelle walk the first time was quite fun because it looked like she was like a sort of floating on air, she was like a hovercraft," Branagh, 50, told Us Weekly at Sunday's NYC premiere of the film, hosted by Quintessentially. "Her knees seemed to be welded together in this dress that simply didn't allow a human being to put one foot in front of the other, and so it seemed like she started levitating."

In the film, the British Oscar winner plays the great actor and director Laurence Olivier, who starred alongside Monroe in the 1957 film The Prince and the Showgirl.

Williams has also opened up about her intense transformation to channel Hollywood's most famous blonde. "Physically and vocally, everything about her is different from me. I've kind of gone to school and had teachers to help me understand Marilyn, so I could project an essence of her," she told the Daily Mail.

Sign up now for the Us Weekly newsletter to get breaking celebrity news, hot pics and more delivered straight to your inbox!

Want stories like these delivered straight to your phone? Download the Us Weekly iPhone app now!