The actress rose to global fame for her portrayal of the French singer in the 2007 Olivier Dahan-directed biopic, with the role garnering her the Academy Award for Best Actress.

Speaking about acting as the iconic star during an appearance on The Graham Norton Show, Cotillard admits that Piaf stayed with her for a long time after filming wrapped.

"It was the first time I had trouble getting rid of a character. I was ashamed of that because it was a job and as an actress I shouldn't have been affected by a role," she shared. "But I had lived six months with her and entered another dimension - I didn't see my friends or family because when I did they would find me weird, with my shaved head and eyebrows, and I didn't like it."

Accordingly, the 41-year-old found that it took quite a while for her to move on from the character, as she had invested so much time and energy in mastering her portrayal. And she can still lip sync to perfection Piaf's song, Non, je ne regrette rien.

"When you do movies a lot of the time you fall in love with the person, and then at the last 'cut' you will never share your life with that person again - it can be brutal," said Cotillard.

But the Paris-born star explains that she had a very different experience on set when working with her husband Guillaume Canet on the 2003 film Love Me If You Dare. One day Cotillard dared her actor beau to take a Polaroid camera to set, telling him to get a "picture of an a**e" and that he had five minutes to get it.

"I should have said I wanted a woman's bottom because one of the crew was happy to pull down his pants straight away!" she laughed.