First Night: Othello, Donmar Warehouse, London

Fresh replaces the familiar with Ejiofor and McGregor

The secret of the success of Michael Grandage's extraordinarily fresh and new-minted production is that, for once, nothing in this familiar tragedy feels like a foregone conclusion.

That's partly thanks to the canniness of the casting. With Chiwetel Ejiofor as Othello and Ewan McGregor as his nemesis, Iago, the production finds two actors who can go against the grain of current notions of how these roles should be played and who can furnish us with new insights into the hero's downfall.

The cynical view is that Othello is a fit of murderous jealousy waiting to happen. Insecure in civilian society, he wraps himself in the security blanket of grandiloquent rhetoric and is more in love with the idea of being loved by a white girl than in love with Desdemona. Iago, meanwhile, is an ill-favoured, impotent, repressed homosexual. He may not know precisely why he wants to destroy the Moor, but he's a dab hand at diabolical planning and his plot goes swimmingly, not least because Othello proves such an easy, if ironic accomplice.

Beautifully lit so that some of the scenes seem to have been painted by Titian, this sparely staged production is revelatory in the way it knocks for six such a mean-minded interpretation. Delivering the verse with a warm expressiveness, Ejiofor's magnificent, exotic-accented Othello exudes a calm charisma and has the kind of spiritual presence that would make you dread doing anything shabby in his presence. Never has an Othello been less quick to jealousy, nor has more movingly revealed the agony as well as the anger in his mistaken sense of betrayal.

There's nothing deluded or self-hypnotising, however, in Ejiofor's love for Kelly Reilly's Desdemona, here visually ravishing in her defencelessness, if over-childish of speech. But precisely because he has taken such a brave imaginative risk in marrying her, it leaves him vulnerable to the insinuations of Iago. A boyish, bearded Ewan McGregor brings an easy affability to the public side of the role (for once, you can understand why everyone is prepared to place their trust in him) and he drops the mask in order to assume a slightly louche, though insufficiently unsettling, intimacy with the audience in the soliloquies.

In his Machiavellian machinations, this Iago has not worked it all out in advance and at one point he ponders his next step while sloshing through a Venetian gully. Then inspiration strikes and seems to engender the storm that destroys the Turkish fleet, thus creating the lull in Cyprus that gives him the time to put his poison to work.

With first-rate support from Tom Hiddleston's posh, rank-pulling Cassio and Michelle Fairley's fierce and indignant Emilia, this is a terrific Othello and makes one regret all the more that the stars' commitments preclude a transfer, sending the price of tickets on e-Bay soaring to a reported 1,200 a pair.