To get director Guy Ritchie to pick him for the lead in his King Arthur film, Charlie Hunnam offered to physically fight the other finalists for the role, Man Of Steel (2013) star Henry Cavill and Jai Courtney of Suicide Squad (2016).
The 37-year-old British actor relays this story with relish to The Straits Times and other press, although he implies that his offer was a bit of a joke.
But one is not sure whether to believe him, especially given that the muscle-bound Pacific Rim (2013) star would not look out of place in a boxing ring and that his mood seems to oscillate between jocularly amiable and broodingly intense.
He says Ritchie was concerned that he was looking a little weedy at the time, having just dropped about 9kg for the television drama Sons Of Anarchy (2008-2014), about an outlaw motorcycle gang.
"I had lost a lot of weight for the last season because I wanted to feel the physical impact of what was going on emotionally, so I wasn't really my fighting-fit self," says Hunnam.
"And Guy was a little concerned about this. During the two or three days I spent with him, he brought it up about 10 times: 'So, how much do you weigh now, how much can you put on, have you been in many fights in your life', and all of this."
In King Arthur: Legend Of The Sword, Ritchie's modern retelling of the legend, which Hunnam describes as "Lord Of The Rings meets Lock, Stock and Two Smoking Barrels", Arthur is a street-savvy tough guy who grows up in a brothel and must fight to reclaim the throne. It opens in Singapore tomorrow and co-stars Jude Law.
Ritchie's line of questioning irked Hunnam. "Guy knew this was a very physical character and wanted him to feel sort of effortlessly dangerous. But I'm never really interested in the physical - the emotional integrity and the internal is what I spend all my time thinking about," says the star, who is married to jewellery designer Morgana McNelis, 33.
"So I said, 'Bro, do you want to ask me about my size one more time?'" Hunnam recalls animatedly. "I thought, 'Let's turn this into a bit of banter. So I said, 'You know what, stop the camera' - it was in the middle of the audition - 'because I'm starting to lose my temper.'"
Knowing that Cavill, 34, and Courtney, 31, were both being considered for the role too, he said: "I'll fight them both at once for the role and we'll see what's up with the f***ing physicality.
"And he's like, 'All right, calm down, mate.' I really do think that's the moment I got the role. I saw Guy looking at me and sort of thinking, 'Ooh, I like this kid, he's a bit frisky,'" says Hunnam of Ritchie, who helmed the 1998 cult film Lock, Stock And Two Smoking Barrels, about London gangsters.
Ritchie says his goal was to make this contemporary retelling of the Arthurian legend, which dates back to the Middle Ages, "an everyman story".
"One of my biggest challenges was: How do you make King Arthur interesting if he's noble? Because noble isn't interesting. We can't relate to it because we're not that noble. The reality is we're all struggling and that's a scruffy, messy business.
"But that's what we care about and are interested in, so to watch the ascension of a man who's completely dependent on his environment become completely independent of his environment is an everyman story," says the director, 48, who has three children aged two to five with model Jacqui Ainsley, 35, and two sons, 16 and 11, with ex-wife, singer Madonna, 58.
An even bigger challenge for the film-maker was managing the movie's blend of fantasy, superhero and comedy elements with action, special effects, modern music and the distinctive banter of his British gangster movies.
"The trickiest part of making this was finding a consistent tone that would integrate all those elements," Ritchie says.
For Hunnam, the main difficulty was getting comfortable with having Arthur be a little unlikable.
"As an actor, you just want everyone to like you from scene one. It was about trying to find the right balance between cocky and swagger and heart.
"And I love the idea that Arthur was this ignoble and potentially unlikable guy to begin with and, as we start peeling away the layers and start seeing what's the source of some of those things, that you would start to fall in love with him and hopefully root for him."
•King Arthur: Legend Of The Sword opens in Singapore tomorrow.