Becoming one of the most powerful superheroes in the Marvel Cinematic Universe is no easy feat.

It takes months of gruelling, physical training, something that Captain Marvel star Brie Larson learned firsthand over the course of nine months in preparation for her role as the titular character.

Aside from the countless hours Larson had to spend in the gym to build her strength, the actor also had to work on another, slightly surprising aspect of training - her facial expression.

Speaking with talk show host Jimmy Kimmel on 4 March, the Oscar-winning actor explained that her peers were unable to contain their laughter on set as they watched her try to master a solemn, focused, superhero "cool face".

"They're usually laughing at you while you're trying to find it, because it's hard. At least, it was for me. I would just bust up laughing," Larson said.

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The star then demonstrated what her first attempt at a "cool face" had looked like, her deadpan expression prompting laughs from Kimmel and the audience.

Larson explained that the stunt team helped her perfect her superhero demeanour, instructing her to turn around, bend her knees and clench her firsts before slowly turning her head.

Following her appearance on Jimmy Kimmel Live, Larson was photographed on the red carpet of the Los Angeles Captain Marvel premiere wearing a custom star-spangled dress by American luxury fashion brand Rodarte.

Brie Larson attends the premiere of Captain Marvel on 4 March in California (Getty Images)

Larson thanked Rodarte co-founders and sisters Kate and Laura Mulleavy for creating the gown for her, writing on Instagram that wearing it for the occasion was a "dream come true".

One of the highlights of the premiere occurred involved the US Air Force's Thunderbirds squadron flying over Los Angeles landmarks in celebration of the event.

Members of the Air Force, some of whom worked with Larson on the film, also attended the premiere.

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On Wednesday 27 February, the London of Captain Marvel was held at the Curzon cinema in Mayfair.

Female police officers were in attendance at the event to celebrate 100 years of women serving in the Metropolitan Police.

During the premiere, Larson had a heartwarming interaction with an eight-year-old girl, who was dressed in Captain Marvel's signature red and blue superhero suit.