'Rush' director Ron Howard has revealed that he nearly had to cancel making the film, because he didn't think he'd find anyone to play motor racing icon James Hunt.
"The James Hunt casting threatened to derail the movie," the Oscar-winning director tells HuffPostUK.
"Looking at the list, seeing who was available, thinking about it, there was no one who was fitting the mould as well as Daniel (Bruhl) did for Niki (Lauda), and my heart began to sink.
"I began to think we really shouldn’t go ahead with this, it would be compromised."
James Hunt is played by Chris Hemsworth in the film 'Rush', with Daniel Bruhl (right) as Niki Lauda
Fortunately for Howard and cinema-goers, 'Thor' star Chris Hemsworth stepped up, and he came with a glowing recommendation from one of Howard's peers.
"I’d met Chris and liked him, but had no way of knowing if he could be James Hunt, plus he was huge when I saw him, he was Thor," says Howard now.
"But Kenneth Branagh said he really had a lot to offer as an actor. And one day Chris just sent in a self-made audition tape, with some of the script, and it was so cool and such a confidence booster, He had the body language, the beginnings of the sound, he had the attitude, he was transforming himself as a good actor does, and it reinforced what Kenneth Branagh had suggested. Then it was done. We knew we had our movie."
Lauda and Hunt - two very different men with the same goal
'Rush', out in cinemas at the end of the week, tells the story of the legendary 1976 Formula One season, which saw Hunt - British playboy, hedonist, telegenic daredevil - pitted against Lauda, disciplined, quiet, technical - for the title, with only a point separating them going into the final race.
"I don’t think it’s fair to take sides," says Howard of the rivalry between the two drivers.
"I don’t think there was a good guy and a bad guy. It was a rival story, and a duel survival story, and the big narrative question is, whatever is fuelling these guys to compete, including their rivalry, is it going to do them in, are they going to navigate this gauntlet that the 1976 season turns out to be? That’s the tension, that’s the drama."
Ron Howard with Daniel Bruhl, who plays Niki Lauda in the film
Of the two very different men, with whom does Howard most empathise? He answers quickly...
"Lauda… I don’t have that natural confidence and belief that my talent will carry it, whereas James could rely on that.
"I think he wore that as a little bit of a mask. People who knew him came to explain that there was an undercurrent of insecurity and fear, but Lauda tries to leave no stone unturned, and leaves nothing to chance, because he believes that’s his chance to excel, and I relate a little bit better to that."
'Rush' is in UK cinemas from Friday 13 September. Watch the trailer below...