How Hollywood's Jake Gyllenhaal turned himself into the lord of the ring
Director Antoine Fuqua, a dedicated boxer and the man behind Training Day starring Denzel Washington, was determined not to make Southpaw "just another boxing movie".
So when the original lead, Marshall Mathers, better known as rapper Eminem, pulled out of the project, he sought an actor who was willing to truly immerse himself in the role of light-heavyweight boxing champion Billy 'The Great' Hope. Step forward Jake Gyllenhaal.
Round One - Gyllenhaal signs up
Although the actor knew very little about boxing, "the thing that intrigued me from the get-go was the idea that Billy's a guy who has gotten by on his rage and his own anger, made a career out of it, had great success and made lots of money".
"But that anger can actually indirectly destroy you," adds the 34-year-old star, who is sporting a thick beard, jeans and a buttoned-up T-shirt.
Penned by Sons Of Anarchy's Kurt Sutter, Southpaw follows Billy as the knock-on effect of a tragic incident sees him reach rock bottom, before he searches for redemption with the aid of a retired fighter, played by Forest Whitaker.
"This is a story about a man coming to grips with his own anger, and the idea of what it is to be a father," notes Gyllenhaal, who was born in California to a screenwriter and director parents.
Round TWO - Starting from scratch
Gyllenhaal's the first to admit he's not a natural fighter. "When I was a kid, I definitely got into a few fights, but I wouldn't say I was the winner of them," reveals the actor, who played Billy Crystal's son in 1991's City Slickers.
"I'd never really trained like this or even knew how to box before I prepared for this movie.
"There was a part of me that was nervous whether I could pull it off, which is why I think I ended up training as intensely as I did."
Round THREe - Fighting for real
The legendary trainer and fight choreographer Terry Claybon, a former pro fighter who's worked with the likes of Washington, Nicolas Cage and Matt Damon, was enlisted to help ensure Gyllenhaal looked convincing in the ring.
"I had a double, but he never worked in the fights, I had no interest in that," states the actor, whose breakout role was in 2001's Donnie Darko, and was nominated for an Oscar for his performance in 2005's acclaimed Brokeback Mountain, alongside the late Heath Ledger.
"I trained as long as I did so I could actually fight and would be prepared to get hit. Our pact, me and Antoine, was that if you did get hit, then we'd use it, or if you broke your nose or a rib. It would be good for the movie, because you're playing a fighter and that's how it goes."
Round four - Training begins
Over the course of six months, Claybon travelled everywhere with Gyllenhaal, teaching him the intricacies of a boxer's technique, both physically and mentally, in twice-daily workouts.
"Antoine decided he would come with me on the physical journey," says Gyllenhaal, recalling how the film-maker would join him in the first training session of the day.
"It was amazing to have your director there with you, pushing you every day. That motivation and sacrifice is what drove both of us, and I think that energy is in the film."
Kicking off with a run, anywhere from two to 10 miles, the six-hour daily programme included rope skipping, working with mitts and punch bags, learning technique and footwork, and conditioning exercises such as sprints, pull-ups and up to 2,000 sit-ups.
Round Five - Animal instinct
Gyllenhaal's known for transforming his body for film parts, previously piling on the muscle to play a soldier in 2005's Jarhead and the title role in 2010's Prince Of Persia: Sands Of Time, while shedding 30lbs to play a sociopathic cameraman in 2014's Nightcrawler. "I think there is a chemical effect," he says of the process. "In relation to something like Nightcrawler, that had a certain effect on me, which was great for that role. It was really isolating and I was very on edge."
As for Southpaw, he adds: "There was an excitement about doing it and there was a positivity. But ultimately, it also leads to really feeling like an animal, and people encourage that. Not just for the fight sequences, but I would train throughout the whole thing because that same attitude needed to be in every scene."
Round Six - mind over body
The actor's journey to embody his character didn't just stop at the physical level. Gyllenhaal felt that understanding the mindset of a boxer was equally as important in doing justice to the role. "The body will only function as far as the mind," he notes. "I didn't really spend much time doing anything else, or socialising in any other way. After a while, what happens is you pick up the molecules of the world that you're in. I love to make things unconscious as an actor, and that takes time."
Round Seven - a question of life and death
Unfamiliar with the sport before the movie, Gyllenhaal's now an avid boxing fan, having developed a new-found respect for what fighters endure.
"There is a legitimate question of life and death when you step in that ring that's unlike pretty much any sport and anything in society, with the exception of going into the military," he observes. "I think in a way, it's a beautiful metaphor for life, in that you come into the ring on your own, you leave that way and the journey is yours."
Round Eight - the next generation
The actor's an uncle to his actress sister Maggie's two children, but doesn't have kids of his own yet. But if and when he does, he's "absolutely" going to pack them off to boxing classes. "For the discipline, the commitment, the focus, the ability to express," Gyllenhaal says.
"The arts and sport are two things for children that are essential. When I have children, that will always be something I'll want to encourage."
Southpaw is released on July 24