First Night: Equus, Gielgud Theatre, London

He wants it all, that Daniel Radcliffe. Having landed what is unquestionably the best film role for a male teenager, he is now making his West End stage debut in what is for my money the best theatrical role for a male teenager.

Much attention has been focused on this long overdue revival of Peter Shaffer's 1973 play Equus. It is not just the actor who plays Harry Potter trying to make his mark in the West End. It is the actor who plays Harry Potter appearing naked in a climactic sex scene, though to the relief of J K Rowling fans the world over, it's a seamless part of the narrative, not needless melodrama.

The role of a boy who blinds six horses and reveals the reason through a series of interviews with a psychiatrist, was always going to be a tough test for 17-year-old Radcliffe. He risked being exposed in more ways than one. Film critics have been divided on whether Radcliffe's deadpan expression in the Harry Potter movies was a requisite for playing a boy wizard sanguine in the face of adversity, or a limited repertoire of emotions.

In Equus, the demands are greater. Alan Strang is a boy full of repressed passion, guilt and yearnings, aiming to deceive both his psychiatrist and himself, weaving his fantasies of religious worship through the horses in his care, experiencing a passion for them which inhibits his relationship with human beings including a putative girlfriend.

In the event, Radcliffe acquits himself well. He is not the most expressive of actors, and his stage presence will take time to evolve; but from the moment he enters the psychiatrist's office, shoulders hunched, eyes narrowed and singing advertising jingles to avoid questioning, he cuts a compelling figure. As the evening goes on, there are moments when he touches, even if not tugs at, the heart strings. One feels for this boy because one senses from his performance a repression hiding a reservoir of feelings desperate to burst.

If the production is well served by Radcliffe, he is not that well served by the production. The director, Thea Sharrock, fails too often to capture the tension in this psychological thriller; too many of the minor parts are curiously undercast (though Joanna Christie as the girlfriend is convincingly coquettish); the minimal set of four blocks on an empty stage adds little to the overall effect; and it is irritating to see the actors rearranging the blocks at moments of intensity. Having two rows of the audience seated above the back of the stage is simply distracting.

As the psychiatrist, Richard Griffiths commands the stage as he always does; but his was not an interpretation I warmed to. The self-mocking bonhomie that was so effective in The History Boys does not fit as well here. He, like the adolescent he is treating, goes on a journey of self discovery, finding that he envies the boy's passion, envies his capacity for worship - all of it a contrast with his comfortable but passionless, suburban marriage. I wanted more introspection.

But no caveats can fully detract from the punch that this powerful and haunting play still packs, never more than when the horses are on stage - performers (led by actor and dancer Will Kemp) with their heads in cages of wire and metal, moving with serene majesty as dry ice rises from the stage. Dreamlike and disturbing moments.