Scriptwriters Dick Clement and Ian La Frenais were cautious about writing a movie about football - sport doesn't have a good track record in films. But, as they tell Steve Pratt, they have high hopes that Goal!, made with Newcastle United, will score at the box office.

Ian La Frenais wanted to know the football score, worried that if Newcastle United didn't win their match it would cast a shadow over the film premiere he was attending that evening.

Happily, the Magpies' convincing victory over Blackburn Rovers meant smiles for the cameras as Whitley Bay-born La Frenais and writing partner Dick Clement walked down the red carpet into the Odeon cinema at The Gate in the city centre.

Perhaps their movie, Goal! is a lucky omen. "Every time we were filming there, they won. Perhaps we bring them good luck," recalls star Kuno Becker.

The writers are known for comedy more than sport, through TV hits such as The Likely Lads, Porridge and Auf Wiedersehen Pet, but have shown themselves a safe pair of hands into which to place the script for Goal!. This ambitious cinema trilogy follows a Latino player from the slums of Mexico to Los Angeles, Newcastle, Spain and, in the final part, to World Cup glory.

The writers came aboard the project after an abortive start when director Michael Winterbottom left over creative differences. Original star Diego Luna was also missing when filming resumed, meaning scenes he shot during a match at Darlington Football Club were left on the editing room floor. Clement and La Frenais were enlisted after Danny Cannon, the British executive producer of US TV hit CSI, signed up to direct. "We came on fresh with Danny. We essentially kept the story and wrote fast because they were desperate to start shooting," says Clement.

They travelled to the North-East a year ago to look for locations in the North-East. Newcastle Football Club was already part of the project, lending its ground and players for the soccer scenes in return for worldwide exposure.

La Frenais suggested Tynemouth as the location for the home of the former Newcastle scout and player who discovers Santiago in a local game in Los Angeles. Coincidentally, the previous February, the pair were in Newcastle for the Sunday For Sammy charity concert where Clement met Magpies' chairman Freddie Shepherd but "having no idea we would ever be involved in the film".

Odd couple Clement and La Frenais have always seemed an unlikely combination, bridging the North-South divide - one from Essex, one from Tyneside - to create some of TV's most memorable and enduring series. They moved to Los Angeles several decades ago, earning a reputation not just for their own work but as script doctors able to heal ailing screenplays. Pearl Harbor and The Rock are among the movies whose scripts they've tweaked.

Both have an interest in football. Chelsea is Clement's team, while La Frenais supports Newcastle. A scene in Goal! shows ex-pats enjoying a beer and watching televised games in an LA bar, something that's not unknown to them. "There are some games you don't get on the TV," says La Frenais. "Until the last two or three years we used to go to English pubs to watch them. Now we can get most at home. But we've lived through that scene in the pub in the film."

On Goal!, they stuck with the project through the editing process. "That's what Danny wanted and we prefer that," says Clement who, like La Frenais, is now in his late 60s. "Post-production can be a very interesting time. We were in California when Danny got us to write a bit more commentary in the game."

The pair get back home from time to time. Clement returned for a holiday in the summer, spending much of the time watching England's Test cricket matches on TV. La Frenais took the opportunity of coming to the North-East for the premiere to visit friends, dine out in Whitby and stay in Guisborough.

They're well used to the LA sunshine and swimming pool lifestyle, but have retained their essential Englishness - and their accents - enabling them to continue writing scripts set in their home country.

Clement confesses to missing cricket, keeping up with matches on the Net. It can't be long, I suggest, before someone makes a cricket film about England's Ashes victory. But he's aware that sports films are tricky and only a few, like Rocky, manage to pull it off.

The makers of Goal! are banking on links with FIFA and Newcastle United to lend their film an authenticity lacking in previous football movies. The leading actors loved their time filming in the city and the Toon Army's reaction. For Mexican-born actor Kuno Becker, 27, coming to Newcastle to play the leading role of Latino soccer star Santiago was an unusual experience, not least because of the accent and the weather. "At the beginning I thought they were speaking German, then I realised it was the Geordie accent," he says.

"I knew smog from Mexico City but it was super cold in Newcastle. In the trial scene, I couldn't feel my hands or legs. I don't know how the girls do it, they're in mini-skirts. It's crazy. Newcastle is an amazing place and they were great to us."

He spent four months training with the club, sustaining several injuries. "When I saw the city again, it reminded me of broken ankles, a broken nose but also good things like great people, Geordie jokes, black pudding," he says on the day of the premiere.

The fictional footballers filmed at St James's Park on match days, although some cheating was involved, reveals American actor and English football fan Alessandro Nivola, who stars as playboy soccer star Gavin Harris. "We had the challenge, for the sake of some kind of veracity, to inject ourselves into the real world and lives of the club," he says.

"That involved us being in the training camp and doing these stunts - like suiting up in their outfits, crouching down behind the advertising boards and then leaping out on to the pitch at the end of the match with make-up on our knees and spray on our faces to make it look like we'd just played."

After the successful revival of Auf Wiedersehen Pet, last year was a busy one for Clement and La Frenais with BBC adaptations of two novels, Archangel and The Rotters' Club. While publicising Goal! they've been questioned persistently about the likely return of another comedy show, The Likely Lads. Original star Rodney Bewes has been pushing for a new series although he knows only too well that co-star James Bolam doesn't want anything to do with it. For their part, Clement and La Frenais seem certain it'll never happen. They haven't even written a script for a sequel.

Besides they've plenty of other projects. La Frenais tells how they've been approached by someone with access to the Beatles back catalogue who wants them to construct a new 1960s-set musical. They're waiting for an animated feature they've scripted, Flushed Away, to be completed. "We wrote that so long ago and have heard so little about it," says La Frenais. Hugh Jackman, Kate Winslet and Ian McKellen are among those lending their voices to the story of a posh rat from Notting Hill who takes up with punk rats under the city.

The Goal! producers must hope that the writers' magic touch will help them crack the US market with a British football movie. Currently, Clement and La Frenais are polishing the script of Goal! 2, in which Santiago joins Real Madrid. Principal shooting starts next month.

Before that, the Toon Army will undoubtedly let them know what they think of Goal!. Nivola is hopeful, saying fans tended "to be forgiving of us" during filming. "I remember leaving the ground after the first time and going back to my trailer. A Geordie fan who recognised me from the pitch yelled out, 'Harris, you played great'," he says.

No doubt the film-makers are pinning their hopes on fans feeling that Goal! is great too.

* Goal! (12A) opens in cinemas on Friday.