“Diego Maradona” is no polished hagiography. Narrated off-screen by the man himself (and sounding much older than his 58 years), it’s an intimate look at his pivotal years in Napoli in the mid to late 80s, where his life on and off the field became mythical as fame and success combined with sex and drugs, fuelled by money and mafia.

By the admission of those closest to him, he was a splintered madman genius.

There was Diego - the consummate professional: dedicated, loyal, rational and focused. He trained hard, he put in extras and would fulfil his contract with total dedication even when he wanted out.

And then there was Maradona. The maverick sex, drugs and rocking goals legend, who started the party at full-time on Sunday and didn’t stop until Wednesday when the cleansing ritual of training restarted all over again.

Along the way he almost single-handedly took an apparently near-bankrupt side battling relegation to Scudettos and European glory.

With Argentina, he destroyed Falkland War foes England with the cynical Hand of God goal – but then followed it up with one of the greatest goals the World Cup has ever seen, a gaucho dribbling work of genius from one end of the pitch to the other, en route to being World Champions.

If one game reflected his life, it would be that. As the posters say: Rebel, cheat, hero, god. (Interestingly, the wording on the posters seems to change from one country to another, with “cheat” often replaced by “hustler”…or just deleted altogether.)

Four years later, he struck again, shattering Italy’s World Cup dreams at Italia 90 when his spot kick – at Napoli’s own home stadium – helped bring the hosts’ campaign to an end.

For those in Naples, that was the moment he went too far, and the knives came out for now coke-bloated star.

As Italians jeered the Argentine anthem, Maradona curses the crowd: “You sons of bitches…”

The mafia and police protection he had once enjoyed ended abruptly. Phone taps revealed the depths of his round-the-clock sex and drugs self-indulgence.

As his personal trainer Fernando Signorini admits: “Diego has had a life both tremendous and terrible.”

Using only archive footage - some of it from Maradona’s own personal collection - it takes you inside the tortured family life, the jubilant dressing rooms and the drug den nightclubs.

If there is one complaint it’s that the actual football takes a very low priority. Too often the action footage shows only moments of brilliance ended by a hack tackle on Maradona rather than one of his stunning strikes.

It’s nit-picking though because the insight the rest of the movie gives is incredible.

Right from the start you are literally alongside Maradona from the moment he arrives through the crowded streets of Naples as he pulls into San Paolo Stadium for the very first time to be unveiled to 85,000 waiting fans in 1984.

Wearing an opulent fur coat, he tells the camera he made the move from Barcelona because: “I’m interested in glory, not money.”

But he admits at Barcelona: “I asked for a Ferrari and I got a Fiat.” (NB – He arrives at Serie A strugglers Napoli in the back of a Mk1 VW Golf.)

Seven years and multiple silverware later, in 1991, he’s run out of town by police and football, banned, washed up and unwanted.

On TV 13 years later, he’s so fat he can barely sit up in his chair as he admits he’s just been released from psychiatric hospital after a life consumed by drugs and self-indulgence warped his mind beyond even the reach of conventional rehab.

At Russia 2018, he’s manically cheering on Argentina in an apparent cloud of coke dust as a FIFA guest in a corporate box before collapsing and going home in an ambulance.

The movie closes with recent footage of him trying to play with some kids in a street football pitch, overweight, unfit and in agony with every exertion - and yet still with talent and skill to spare.

The movie’s release will doubtless resurrect the long running rows about who is the greatest, Pele or Maradona - but that misses the point. They are of course both otherworldly geniuses.

One led the bland-by-comparison life of a champion and a hero, while Diego Armando Maradona was a self-indulgent, self-destructive legend.

Like George Best before him, Maradona’s life has been one of brilliance, elation, controversy and mythology.

Like Best, rolling around with Miss World on a four poster bed covered in cash while drinking champagne, you could ask Maradona where did it all go wrong?

But for all the drama, you suspect, like Best, he will just look at you incredulously.

His has been a life well-lived - and the movie is a charge sheet, confession…and celebration.

Diego Maradona opens in cinemas tomorrow, July 25.