Knightley was terrified of shooting a scene with Dench in Pride And Prejudice, but soon regained her confidence when she realised the stalwart star was only human.
Knightley tells British movie magazine Empire, "I was absolutely s**tting myself before meeting Judi Dench.
"But you know what happened? She couldn't remember her lines.
"And she's getting quite embarrassed and a bit flustered. But still being lovely, and amazing and fantastic.
"You just go, 'Ooh, okay, I'm not that s**t, because if she does it and still gives great performances, then maybe I can too."