The Smashing Machine - a sports drama about MMA legend Mark Kerr - took just $5.9m (£4.3m) at the US box office, an underperforming debut for one of Johnson's films; his successes include the Fast & Furious franchise and Jumanji films.

Writing on Instagram, the star framed the results as a creative achievement rather than a financial disappointment.

"In our storytelling world, you can't control box office results," he wrote. "But what I realised you can control is your performance, and your commitment to completely disappear and go elsewhere.

"I will always run to that opportunity," he continued. "It was my honour to transform in this role for my director Benny Safdie.

"Thank you brother for believing in me. Truth is this film has changed my life."

He signed off his post saying: "With deep gratitude, respect and radical empathy, DJ."

Variety wrote that the film cost $50m (£37m) “to produce (and plenty more to market)", and early estimates predicted a healthy opening weekend of about $20m (£15m).

The Smashing Machine marks a rare dramatic role for Johnson, who is best known for action franchises and family-friendly turns, including voicing a character in Disney's Moana animation.

He plays Kerr, a fighter who dominated the early, unregulated days of the Ultimate Fighting Championship (UFC) in the 1990s - before rules such as "no eye-gouging" were introduced.

The film was developed from a 2002 documentary about Kerr with the same title - which contrasted the fighter's achievements with more intimate scenes, as he battled substance abuse and fought with his girlfriend.

Johnson, a former wrestler, saw parallels to his own career in the documentary, and cherished the idea of dramatising it for several years.

Premiered at the Venice Film Festival earlier this summer, the arthouse biopic film received rave reviews.

"The actor delivers an intoxicating mix of blood, sweat, tears, protein and total helplessness," wrote The Hollywood Reporter.

Empire magazine called it "the best work of his career".

However, audiences failed to materialise.

As well as the disappointing US box office, the film came fourth in the UK charts, making just £863,078 - less than the Downton Abbey: The Grand Finale, which has already been in cinemas for a month.

Audience tracking for the US suggested that 70% of ticket-buyers were male and 64% were between the ages of 18 to 36 - the traditional audience for Johnson's action movies.

Only 8% were above 55 years old, a key demographic for arthouse releases.

Those who attended the film were apparently disappointed in the lack of action scenes, with audiences giving a lukewarm "B-" grade in exit polls, Variety said, while exploring why the film "flopped in its box office debut".

Johnson tried to temper those expectations in the run-up to the release.

"It's not a fight movie, it's a life movie," he said at the red carpet premiere last month.

"Mark Kerr's life represents so much of everyone around the world, but not, 'Oh, he's the greatest fighter on the planet,' but more so, 'Oh, he struggled with pressure and how to deal with pressure,'" Johnson explained.

"At one point, he was the greatest fighter on the planet, and then he lost - and he had a hard time reconciling with that loss.

"He overdosed twice. He's lucky to be alive, and I'm so happy that he is alive.

"Because as you know, films like this where they're a bio film, a lot of times, the main subject isn't alive... So, I'm so thankful that he is," he added.

Despite the box office disappointment, Johnson and his co-star Emily Blunt are still in the mix for Oscar nominations next year.