Eddie Redmayne had "nine months of sleepless nights" while shooting The Theory of Everything.
The 32-year-old actor was so concerned about what Stephen Hawking, who he plays in the film, would think of his portrayal that he struggled to get off to sleep every evening after filming as he was too busy worrying whether or not the physicist would like the motion picture or not.
When asked how scared he was when he was making the movie, he said: "Terrified. I'd met Stephen and he was never going to say, 'I'm thrilled you're doing this, you're going to be amazing.'
"It was nine months of sleepless nights, thinking, 'Will he like it?' "
AdvertisementAdvertise with NZME.
But Eddie needn't have worried too much as when Stephen - who was diagnosed with motor neuron disease aged 21 - watched the film he told director James Marsh he thought he was watching himself in some parts of the movie.
Eddie said: "That was the greatest review ever. I want to retire."
But the star didn't get quite the response he wanted on his first meeting with the 72-year-old author - who communicates with the aid of a computer and speech synthesiser - as he admitted the rendezvous was "embarrassing" because he didn't know what to say to him and ended up talking about astrology.
He added to Time Out magazine: "I filled the room with hot air - I struggle with silence.
"The most random thing I said was so bad. He was born on January 8, 300 years to the day after Galileo, and I said, 'It's funny because I was born on January 6, so we're both Capricorns.'
"He looked at me and then he spent a few minutes typing.
"This was the second thing he said to me, in his iconic voice, 'I'm an astronomer, not an astrologer.' Which is hilarious but excruciating - he's not Mystic Meg!"
- Bang! Showbiz