LSO/Rostropovich, Barbican Hall, London

A gloriously inspired Prokofiev

It was while watching "Slava" Rostropovich clench his fists during the climax of "Juliet's Tomb scene" that I suddenly thought to myself, "mark this moment: you'll want to tell your grandchildren about it." And yet the idea of a semi-staged Romeo & Juliet had seemed potentially problematic. Presenting a two-and-a-half-hour ballet in concert is difficult at the best of times. There's no "symphonic argument" to hold you captive. There are no voices to explain the story, just dances, more dances and the odd expansive pas de deux. But Thursday's novel solution worked a treat.

Slava is on the eve of his 75th birthday, and it was very much his night. The London Symphony Orchestra took centre stage, in a kind of reversed seating arrangement (cellos with their backs to us, woodwinds somewhere behind them) so that Slava's illuminated face peered ghost-like much as it might in a theatre pit. The front stage was initially black and empty, the rear dominated by a bridge where a colourful troupe of dancers would soon enact aspects of the drama. The most memorable episode came in Act III, where a line-up of mandolins strummed Prokofiev's zany "Dance with Mandolins" while Mercutio, Benvolio and Baltasar put on an hilarious mime-play. The tempo was provocatively slow, and the dancers of the Lithuanian National Ballet were a consistent delight. Choreographer-producer Vladimir Vasiliev made creative use of available space, keeping Montagues and Capulets apart, having Friar Lawrence appear from the bridge and making light of what might in less skilful hands have become a fairly serious space problem.

And there were countless telling subtleties in the acting. The way Egle Spokaite's Juliet checked with Nurse before she took the ball-dress, or her ominous toying with her shroud-gown in the last scene. Georgi Smilevski was her ardent Romeo whose own heartbreaking engagement with the dying Mercutio (Valerij Fadeev) was another high point.

Slava himself served as conductor-narrator. His first entrance was spot-lit, and when at the end of the ballet the lovers lay lifeless on the ground, he left the rostrum and kneeled to join their hands together. Others would have made a cheesy spectacle of themselves, but not him. Principally because his musical performance was so consistently inspired, tender in the love music, aural beefcake in the "Dance of the Nights", relentless for "Tybalt's Death" (although Aleksandr Molodov's dancing helped) and with exactly the right sense of regretful resignation at the close. The LSO coped wonderfully well but then with Berlioz's The Trojans on their CV, you'd have expected that. And there were Prokofiev's smaller dances, such as the revisited (and expanded) "Gavotte" from the Classical Symphony, which the LSO played with relish, or the touching "Aubade" (more mandolins) from Act III.

Indeed, you might say that Slava became Prokofiev's bittersweet music in all its passion and adorable quirkiness. It was hardly surprising when, after taking countless bows, he grasped and proudly paraded the real star of the show: Prokofiev's full score of what is surely the 20th century's greatest ballet.

The LSO/Rostropovich 75th birthday series continues at the Barbican until 27 March. Details and booking on 020-7638 8891 and www.lso.co.uk