VIN Diesel bursts into a quiet hotel room, his team in tow, brandishing a speaker attached to his mobile phone.
The Hollywood action man then selects a disco track to blast out (the 1974 Redbone tune Come And Get Your Love) and proceeds to shake his gym-honed body to the beat, as an assistant films proceedings for the star’s “archive”.
It’s not exactly the entrance you’d expect from the Hollywood tough guy, known for portraying gravelly-voiced, burly bruisers in films such as xXx and the Fast & Furious franchise.
But then, Diesel’s latest acting gig couldn’t be further removed from the usual “hard man” roles, which have helped earn his Facebook page almost 82 million “likes”.
The 47-year-old former bouncer provides the voice for a giant tree creature named Groot in the Marvel action movie Guardians Of The Galaxy (which features the Redbone song on its soundtrack).
Groot and his fellow Guardians, a quintet of intergalactic misfits led by adventurer Peter Quill (Parks And Recreation star Chris Pratt), must ensure that a potentially destructive orb doesn’t get into the hands of a power-hungry villain called Ronan.
Loyal, kind and mighty, Diesel’s character takes the notion of a strong, silent type to the extreme – he can only communicate using three words (“I Am Groot”) and a series of grunts.
“It’s the most innocent character I’ve ever played, clearly, which is why I’ve kind of been so silly,” Diesel says when he settles down post-dancing, his sizeable muscles packed into a dark T-shirt and combats.
“I’m not talking about heavy issues that I’m usually talking about with the movies I make... I get to have fun.”
It’s been a difficult few months for the New York-born actor, whose friend and Fast & Furious co-star, Paul Walker, was killed in a car crash during a break from shooting the hit franchise’s seventh film last November.
A hush descends on the room as Diesel discusses finishing the film without his friend, whose brothers were drafted in to help complete his unfinished scenes.
“It was the hardest film to do – and blessed, because there was such a sense of family and coming back. But surreal,” he says, looking downwards as he speaks.
“You would never imagine that you would ever have to mourn someone so close to you, and simultaneously pretend that they’re sitting next to you. It’s kind of a strange thing to have to do as an artist, and as a human.”
Voicing the role of Groot shortly after the tragedy was a “very healthy and therapeutic thing to do” for the actor.
“When we deal with death, our appreciation for life is represented in so many ways,” he adds. “We appreciate everything that’s alive, the very trees in our backyard. And this character Groot celebrates life, in so many ways.”
Diesel, who has two children with his model girlfriend Paloma Jimenez, says it was his three-year-old son who encouraged him to play Groot.
“I remember someone in my office saying, ‘No, you’ve got to play this or that, what the hell are you going to play a tree for?’
“I went to the living room and showed my children and said, ‘Which character do you think Marvel wants Daddy to play?’, and my son pointed to the tree.”
He continues: “Jump cut to him seeing the movie with me... As I was riding home, my son was looking out the window at trees and he said, ‘Daddy, look, it’s your brothers and sisters’.”
Director and co-writer James Gunn supplied Diesel with a special script for his stints in the voice-over booth.
“With every ‘I Am Groot’, on the right hand side of the page was a paragraph or a sentence of what Groot was really saying,” the actor explains. “So that was how I was trying to get the meaning into each ‘I Am Groot’, and make each of them different.”
Diesel, whose breakthrough role came in the 2000 sci-fi thriller Pitch Black, and who has also worked as a producer, director and screenwriter, insists that voicing a monosyllabic tree alien wasn’t easy.
“I was being challenged as an actor, as a thespian – the idea of playing a character without any facial mannerisms or allowing your body physicality to play into the character, and being limited to such a small vocabulary,” he says.
Despite never appearing on screen, Diesel wanted to understand Groot’s movements, and so donned a pair of jumping stilts.
“I wanted to feel a little bit how it would be to be this towering figure. It played into the character and somehow affected my performance,” he explains.
Guardians Of The Galaxy is now on general release