If, as David Mamet suggests, the perfect drama is like the perfect ball game, Lloyd Evans's new play is like a nice knock-up in which neither party breaks into much of a sweat.

It's set in Wimbledon fortnight at the rented house of the British number one, posho from Monaco Madeleine Rochester, and Cedric, the cockney ex-con assigned to mind her. Unbothered by meddling trainers, managers, nutritionists or friends, they settle into mutual antagonism - with an undercurrent of attraction - as Madeleine's freakishly successful tournament continues. They spat a bit, but not a lot, and you wonder what Evans, the drama critic for The Spectator, told himself the point of all this was.

The dialogue throws up the odd sharp exchange and there's a promising moment just before the interval when the light comedy subsides and Cedric rants about why he embraces criminality: “Humanity is full of fools and cowards who have never lived.” Great. Shame that it doesn't really chime with what's gone before and, worse, that it isn't really developed by an unconvincing second act.

Would the British number one - even an ageing, flighty, disillusioned British number one - really smoke and get drunk the night before her big match? Would Cedric really try to nobble one of her opponents? You might accept such contrivances from a script that goes all out for laughs, but this is a draft or two shy of going all out for anything.

No blame to the actors, Rachel Pickup and Sam Spruell, who enter into their rallies with as much spirit as they can muster. And if Ben Stones's cramped living-room design tends to confine them between bits of furniture, it's the most excitingly authentic part of the show - cloyingly middle class, with books by Dick Francis, Ken Follett and Chris Patten on the shelves.

But Tamara Harvey's production, understandably, cannot get much heat from the characters' exchanges. Evans is a good writer, but this is the story of a Brit getting to the final of a grand slam event in which, somehow, there's never much at stake on stage. A passable two hours without half the drama of Today at Wimbledon.

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