The actress appears alongside a stellar line-up including Penelope Cruz, Nicole Kidman and Dame Judi Dench in the upcoming film.
But it was Day-Lewis who made Loren nervous - because she felt overshadowed by his acting ability.
She says, "Daniel is incredible. He is hypnotic, magical, beautiful and brilliant; but he is also very scary. Every time I did a scene with him he was so deep and so real that it was almost intimidating."