Dir: Sharon Maguire. UK. 2001. 90minsTBC.Bridget Jones's bestselling diaries made the fictional thirtysomething singleton Britain's most successful under-achiever of recent years, and the screen version of her intimate journal bears all the signs of becoming the UK's biggest film hit since Notting Hill.

Domestically, massive advance publicity and media attention will guarantee dazzling opening figures, while the reputation of the books in the US should secure equally healthy business there.

If the film is to build this into solid longer-term box office, then it must establish itself as more than a chick flick with appeal to the obvious demographic. Instead, it will need to position itself more broadly as a modern social satire-date movie that can attract those men lured along earlier this year to What Women Want by the presence of Mel Gibson (but without a comparable male character for them to root for).

The diaries have been published in some 30 countries, but in territories where the book has been less of a cultural phenomenon than on its home turf, the film's performance will, to a greater extent, be review-driven, aided by the names of Renee Zellweger in the title role and Hugh Grant as the second male lead. Prospects in all ancillary media are, as Bridget would put it, v. v. good.

A character invented by journalist Helen Fielding, Bridget Jones herself is a none-too-effective publishing PR in her early 30s with a mass of addictions - cigarettes, drink, junk food and lottery cards - who aims to achieve happiness by losing weight and finding true romance. Her diary chronicling the ongoing chaos of her life and her farcically unsuccessful struggle to realise her modest ambitions made a low-key debut in 1995 as a weekly column in UK national newspaper The Independent, but gathered momentum after Fielding was encouraged to rework it as a book.

When it did go into paperback it became a cult success, spawning a sequel, The Edge Of Reason. Like such American TV sitcoms as Sex And The City and Ally McBeal, and Hollywood movies such as Waiting To Exhale, its success has been generally attributed to the swelling numbers of single thirtysomething women experiencing difficulties in reconciling the conflicting demands of love and career.

Structured much like the novel, the movie traces a year in the life of its heroine, beginning with Bridget's ghastly Christmas-New Year celebrations with her parents and their neighbours. During the following months, she has an ill-advised fling with her flirty caddish boss (Grant, offering an enjoyably acerbic variant on his usual bumbling screen image); observes her parents' marital problems after her mother makes off with a sleazy presenter from a home shopping channel; makes her own foray into television when she swaps her publishing job for a gig as a news presenter; spends many a long, boozy evening with her gaggle of sweet, but hopelessly dysfunctional, female and gay friends; and gradually warms to the subtle attractions of Mark Darcy (Firth), a stuffy, though ultimately charming (and extremely rich), human rights lawyer.

Boasting the same production company (Working Title), star (Grant) and co-screenwriter (Richard Curtis) as Four Weddings And A Funeral and Notting Hill, Bridget Jones shares those two earlier films' comic tone and similar themes of the peculiarly British knack for self-deprecation and underachievement, both professionally and romantically. As in Fielding's book, there are also deliberate parallels with Pride And Prejudice, both in the name of the leading man and in the presence of Firth (who played Mr Darcy in the recent BBC adaptation of Jane Austen's classic) in this role. Grant also has his own indirect link with the original novel, which takes a passing potshot at the actor's real-life dalliance with a Hollywood hooker.

Curtis's co-scriptwriter, along with Fielding, is Andrew Davies, distinguished for his television adaptations of literary classics, including that same BBC version of Pride And Prejudice. And the film's director - the documentary film-maker Sharon Maguire making her feature debut - is a friend of the author, acknowledged at the front of the novel, as well as being the model for one of Bridget's best friends, also called Sharon. The in-casting extends down to relatively small roles such as the lecherous tabloid news producer played by Neil Pearson, who UK audiences will remember as much the same character in the TV comedy series Drop The Dead Donkey. The writers Salman Rushdie and Jeffrey Archer contribute cameos as themselves.

At times, this all threatens to add up to an air of smug and incestuous London media-set clubbiness, so the choice of an American actress for the leading role - greeted, when it was announced, with some hostility in the British press - turns out in many ways to be a shrewd decision. The film stands or falls by whether one accepts Zellweger's central performance and, sporting a credible British accent (if one several social notches above the level you would expect of her character), she lends Bridget an exuberance and sexiness undiminished by the fact that she gained at least 14 pounds for the role.

Some fans of the book may find her too sweet and fluffy for the character (Bridget had a sharp tongue on her when required). Still, it's refreshing to see a weight-obsessed heroine who really is on the pudgy side, even if the actress is often shot in a way which does her no favours, with stringy hair and a flushed, bloated face.

Grant and Firth are well-placed as the male leads, although in its anxiety to present itself as a romantic comedy, the film gives short shrift to the other supporting characters - notably Bridget's three best friends and sitcomy mother (Jones) - although Jim Broadbent stands out as her gentle, brow-beaten father. It could also be argued that, in cutting many of the books' topical references to current events of the mid-1990s, the focus of the film has been further narrowed. Maguire's comic touch is a little heavy at times, but technical credits are, overall, polished.

Prod co: Working Title. Co-prods: Universal Pictures, Studio Canal, Miramax. Domestic dist: UIP. Exec prod: Helen Fielding. Prods: Tim Bevan, Eric Fellner, Jonathan Cavendish. Scr: Fielding, Andrew Davies, Richard Curtis. Cinemaphotography: Stuart Dryburgh. Prod des: Gemma Jackson. Ed: Martin Walsh . Music: Patrick Doyle. Main cast: Renee Zellweger, Colin Firth, Hugh Grant, Gemma Jones, Jim Broadbent