Kate Beckinsale wanted to ban her daughter from auditioning for a movie in case she was "a disaster." Producers on "Everybody's Fine" needed a young actress to portray Kate's character as her younger self and asked if Lily, then eight, would try out.
Kate feared Lily might be upset if she didn't get the part, but the youngster managed to change her mother's mind.
Kate explained: "They needed flashbacks of all of us being children and they asked me if my daughter Lily would audition. I said no because I thought she'd be on the set, and if she didn't get it, it would be such a disaster."
"But she insisted on auditioning, and got it, and had her three scenes with Robert De Niro, which I thought was absolutely wild at the age of eight."
Despite previously saying Lily did not want to follow her or her father, Michael Sheen, into acting, Kate admits her daughter, now nine, enjoyed the experience and bonded with her screen legend co-star.
She added to Capitol File magazine: "Robert couldn't have been nicer. I think it was a very personal, emotional project for him and he really wanted us all to feel fatherly-daughterly with him."
"He was absolutely lovely and kept feeding everybody cannolis, these little pastry desserts. Lily was a total fan for life once he introduced her to cannolis - the allegiance was set."
Kate, 35, has previously confessed to having had a crush on Robert.
When asked about working with him, the actress - who is now married to director Len Wiseman - said: "I was kind of intimidated, because I had a picture of him on my fridge at university, so I was a bit shifty about that."
"You sort of feel like you have to confess that to somebody. There's sort of a slightly creepy thing to it."