avid Schwimmer – yes, the Friends alumni - makes his directing debut - with a British farce, no doubt. With the spasmodically amusing Run Fat Boy Run, Schwimmer is behind the cameras, while Simon Pegg (the offbeat star of Shaun of the Dead and Hot Fuzz) stars as Dennis, a born loser who competes for his ex and their five-year-old son's attention with her American lover in a marathon.

Dennis, whom we meet in mid-panic attack on his wedding day, is a man clumsily chasing after his dreams. Five years earlier, you see, the dumbass was about to marry the stunning Libby (gorgeous Thandie Newton). She was pregnant with his baby. It was going to be a big ceremony. And Dennis? He scrambles for the exit.

As a director, Schwimmer - who actually directed numerous episodes of Friends - underlines the jokes and adds exclamation points

Time goes by, and now he's a paunchy watchman at a posh lingerie shop and living in a basement flat. He is barely making ends meet on his salary. He’s such a loser that little children give him the middle finger on the bus. Coming to the realization, in true rom-com fashion, that Libby is the one for him after all, he spends the rest of the film trying unsuccessfully to win her affections back. This is made more difficult by Libby's new significant other, rich, macho American businessman Whit (Hank Azaria).

Dennis wakes from his ever-say-die funk to announce that he will run in a London marathon against Whit, even though getting up the steps into his flat can be a challenge for him, pale, pudgy and puffing away on an endless chain of cigarettes. This is when Run, Fat Boy, Run finds its footing.

It's a romantic comedy told from the male perspective, with Pegg's character dividing his down time between doing the good dad thing with their young son Jake (Matthew Fenton), and a plan to win his ex-girlfriend back.

, but a softer touch probably wouldn’t have helped. A US import written and directed by Americans (screenwriter Michael Ian Black and director Schwimmer), Run Fatboy Run comes off as somewhat artificially imposed on British sensibility, and a long jog away from being funny.

Pegg does have a brilliant face for comedy, especially when he does his desperate, ingratiating smile – and certainly is game, pretty much turning the pic into a solo turn – and the other bright spot is Irish comedian Dylan Moran, who plays Libby's charmingly dissolute cousin. But, in the end, everything else about Run, Fat Boy, Run is formulaic. The laughs are few and forced, delivering less than you'd hope for.