LONDON, Sep 12 (Reuters) Romantic comedy ''Run, Fat Boy, Run'' sprinted to the top of the UK box office in its opening weekend, edging out Keira Knightley in ''Atonement.'' The story of a flabby security guard signing up for a charity marathon to impress an old flame is the directorial debut of ''Friends'' star David Schwimmer and took 2.01 million pounds, according to Screen International.
''Atonement,'' the screen version of Ian McEwan's acclaimed novel of guilt and remorse, is widely tipped as an early contender for the 2008 Oscars.
Also starring James McAvoy, the film took 1.6 million pounds to go straight in at No. 2.
Third was last week's chart-topper ''The Bourne Ultimatum,'' based on the Robert Ludlm thriller, while down two places at four was the story of a mismatched couple with a problem after a night of passion, ''Knocked Up''.
Down to five from three was John Cusack in horrr movie ''1408,'' based on Stephen King's tale of a writer stuck in the hotel room from Hell.
At six, down two places, was ''The Simpsons Movie'' whie at seven down from five was police buddy film ''Rush Hour 3.'' Down one place at eight was ''Harry Potter andthe Order of the Phoenix'', based on J.K. Rowling's fifth book about the young wizard, which has now taken 48.9 million pounds in its nine-week UK chart run.
''Bratz: The Movie'', which portrays four schoolgirls defying attempts to break up their group, was unchanged at nine while down two at 10 was robot action fantasy ''Transformers.'' REUTERS AR KP0844