"There are no good football films," says Asif Kapadia. "And I say that as a football fan. Either the actors can't play, or the players can't act. And the crowd scenes are never believable. It all looks fake. Always does."
Always? Not quite. The 47-year-old director has just made the exception. His new film, Diego Maradona, retells the great Argentine player's life story through archive footage and interviews we can hear but don't see: a talking-head-free zone. It's the same format he used for his films about Formula One driver Ayrton Senna and singer Amy Winehouse — the latter won the Best Documentary Oscar in 2016.
Yet Kapadia and his regular editor, Chris King, are the first to acknowledge that fakery, of a sort, has been central to all three projects. "There's a misconception that documentaries are somehow real," Kapadia says. "That we just find a lot of videos and join them together, and the interviews sit perfectly on top. But they're every bit as constructed as animations or Marvel visual effects."
Sitting in front of a computer containing the weeks of footage from which Diego Maradona was whittled, King, 52, describes the making of the three films as "a strange process".
"We're fictionalising these people, thinking of them along almost mythical lines. But at the same time, we're trying to find versions of them that feel honest and true."
His monitor fills with an amateurish shot of the Napoli football team bus pushing through crowds as it arrives at the last match of the 1986-87 season — a turning point in the club's history, as Maradona propelled them to a hitherto-undreamed-of league victory. The clip is wobbly, flickery and unintelligibly shrill. But when King strips out the original audio and adds cinema-quality sound effects, painstakingly matched to the action on screen, somehow it becomes a mesmerising tracking shot, teeming with eye-catching cinematic detail. "You couldn't stage this," he grins.
The additions are subtle, the effect extraordinary. They change the image from home movie to movie.
"We found really early on that the way to make something that looks bad look good is to make it sound good," Kapadia explains.
On Senna, when they stripped out the rambling commentary from pre-race helicopter shots, the footage took on a foreboding air — "the perspective of a witness hovering far above", as King puts it. That became instrumental in setting the scene for the tragic conclusion: Senna's death, aged 34, in a crash at the San Marino Grand Prix. Similarly in Amy, after he'd removed the ambient paparazzi racket, videoed scenes of the singer being chased down the street felt less like show business antics than a pack hunt. "What's familiar," adds King, "can distract you."
Not that Kapadia — whose debut feature, The Warrior, was a Himalayan-shot wilderness epic — set out to make three films without shooting a single frame himself. Senna was originally planned as a standard talking-heads affair: 40 minutes of fresh interviews, the same again of archive material, and 10 of charts and graphics. But during the eight-month negotiation between the production company, the Senna family and Formula One, Kapadia found himself browsing YouTube to see what was already out there, and building it into a first draft, just for something to do.
"After a while I looked at it and thought, 'This is amazing', " he says. "My instinct was, 'I think it's all here'."
His producers were anxious, and tried to tempt him with a 3D camera to shoot his own in-car material. "I was like, 'Yeah, but Senna won't be driving it'." Instead, he talked them round to the scrappy, shaky original footage, "the real thing fiction spends millions trying to recreate".
King only came into the picture when production was wearing on longer than expected: Kapadia remembers bristling at the thought that another pair of hands was "being brought on to save the film". Yet King's genius for injecting images with meaning and mood proved the perfect foil to Kapadia's flair for visual storytelling, and a creative bond was soon forged.
Rather than look to documentaries for inspiration, they referenced great character-driven stories: Amy was Romeo and Juliet; Senna and Diego Maradona were guided by Martin Scorsese.
Diego Maradona barely mentions the 1990 World Cup, even though its subject captained Argentina to the final. It also zips through his early career, including, in a brief prologue, an eventful two years at Barcelona — a section of Maradona's life that once accounted for 20 hours of edited footage.
"You start by cutting in a detailed way, then once you know what you've got, you feel able to lose the whole thing."
King scrolls through some memos he made on his iPhone mid-commute when he and a team of six researchers started sorting through the Maradona files in early 2017, which included a trove of previously unseen footage shot in the 80s for a never-completed vanity biopic.
One note reads: what does he want and why does he want it? Another runs: guilt. split identity. self-worth. "It's as if we were talking about an invented person," says King.
Maradona is the duo's first living subject, though he proved so elusive, the film was largely made without his input. Kapadia was allowed just three interviews, each one heavy on rigmarole. So much hinged on the last that the director had three researchers listening in remotely, feeding him tips through an earpiece and on his laptop. Maradona has yet to see it: he didn't turn up to its premiere at Cannes last month, and has demurred whenever Kapadia has offered to drop by with a DVD.
King recognises the reluctance from his days cutting fly-on-the-wall shows: the initial ego boost of the project's existence is soon replaced by the dread of having an outside perspective on the more intimate aspects of our lives.
"Everyone has a version of themselves they're comfortable with, that rationalises the misdeeds and puts the mistakes in context," he says.
• Diego Maradona is in New Zealand cinemas from August 8.