Last night I watched a man die, slowly and horribly. I shan't tell you how it happened because if you have time you really ought to go and see for yourself when the same man dies in the same way, apparently for real, at a future performance.

Simon Keenlyside as Wozzeck and Endrik Wottrich as the Drum Major in Wozzeck (Royal Opera)
Simon Keenlyside as Wozzeck and Endrik Wottrich as the Drum Major in Wozzeck (Royal Opera)
(c) Catherine Ashmore/Royal Opera
Okay, so like much else in the Royal Opera's Wozzeck it's only an illusion, yet so graphic is the anti-hero's demise at the end of Berg's opera that only half the brain is shocked by it because the other half is trying to puzzle out how it's done. This inescapable shard of detachment is one of several blips in an otherwise absorbing production by Keith Warner, first seen in 2002, that drips with baleful intensity.

The musical performances are shatteringly good. Mark Elder and the Orchestra of the Royal Opera House render Berg's score in passionate colours, conveying the music's tenderness as powerfully as its savagery while bringing unexpected cohesion to its fragmentary structure. He is abetted by a major-league cast whose talents have been expertly assigned to their roles.

Simon Keenlyside, who has not played Berg's disturbed soldier in a fully-staged UK production before, is hardly a revelation – his gifts are too well known for that – but his voice is in prime condition and the concentration with which he inhabits the man is startling. A more sensitive staging than Warner's, though, would allow him to chart his descent into madness rather than placing him in hell from the very start. An asylum setting is all very well – and there's a nice ambiguity as to whether the white-tile set is a hospital or a laboratory – but with his insanity fixed from the outset Keenlyside's Wozzeck has nowhere to go.

After recent embarrassments it is good to hear John Tomlinson in a part that suits his present vocal state: his mad-eyed, enema-administering Doctor, all flowing hair and rubber gloves, is as sinister a creation as Gerhard Siegel's barking Captain, a man as aggressive of voice as he is of demeanour. John Easterlin's very different timbre is well suited to the sympathetic Andres and Robin Tritschler makes a devilishly good impression as the Half-Wit.

To sing Marie, ill-fated mother of Wozzeck's child, the Royal Opera has brought no less a figure than Karita Mattila back to Covent Garden. Shrouded in dowdiness, the great Finnish soprano projects all her character's maternal warmth, carnal desire and primal fear in a mesmerising performance. She sings the tenderest of lullabies to her child (Sebastian Wright), succumbs with abandon to Entrik Wottrich's priapic Drum-Major and cowers in terrified resignation as Wozzeck brings about her end.

The opera's final moments are a disappointment in Warner's hands. The children who taunt Marie's newly-orphaned son are unseen, which diminishes their impact, and the boy himself is so busy freeing his wrists from their restraints that he does not react to them. I've always thought of Wozzeck chiefly as the tragedy of the child, but not here.

- Read Keith McDonnell's Brief Encounter with tenor Endrik Wottrich here