Inviting a non-ballet-literate British director to have a go at a Russian Romeo and Juliet might seem a radical, even rash, undertaking. The Bolshoi, however, likes to think of itself as open to new ideas. The ballet's previous artistic director, Yuri Grigorovich, introduced his own epic 'concept' ballets during his 30-year reign, helping forge the company's heroic style. Now it's trying to leap forward again, replacing his 1979 Romeo and Juliet with an updated version by Declan Donnellan, co-founder of Cheek By Jowl and ex-associate director at the National Theatre.

Donnellan has Big Concepts, too. Without Shakespeare's text, he is free to reinterpret the story of hormone-crazed lovers torn apart by society's prejudices. Forget Montagues and Capulets: this is the world of the nouveau nomenklatura of Moscow, infiltrated by masked mafiosi.

An ever-present chorus, commenting (sometimes noisily) on the action, the crowd also serves as scenery. Dressed as ball guests, they form the balcony that keeps the lovers apart; silhouetted against the backdrop, they wait like vultures for the next crop of corpses.

Nicholas Ormerod, Donnellan's long-term collaborator, provides minimalist sets, constantly changing the stage picture's perspective. The effect is powerful and claustrophobic.

Prokofiev's descriptive score has been drastically edited: key scenes, such as the lovers' first encounter, take place in silence; the mandolin music, a minor motif, becomes a dominant one, mocking the drama.

Donnellan has thus opted to deviate from the two influences that usually determine the structure of Romeo and Juliet as a ballet: Prokofiev's music and Shakespeare's imagery. Fine, in that there's no point in dancers apeing Shakespeare in dumb-show to familiar music; but then a meaningful alternative language needs to be found. The choreographer, Radu Poklitaru, has been entrusted with movement that takes Donnellan's physical theatre into the realm of dance. The result is gibberish. Imagine if a choreographer were to direct actors to yell obscenities instead of speaking poetry. This production has dancers wrestling with an idiom so crude that if it were translated in surtitles, the audience would groan.

When Juliet first meets Romeo in the ballroom, she spreads her legs, skirt rucked up over her face; in their wedding night pas de deux, she nuzzles his bare chest before standing on it; he kisses her foot in an ecstasy of lust. Yet because this is regarded as modern dance, few dare laugh or boo. All credit to Maria Alexandrova as Juliet and Denis Savin as Romeo for compelling us to suspend our disbelief. She is brattish, appealing, headstrong; he, still downy, quivers with intensity. Both invest the silly things they are given to do with such passion that I could kill the choreographer on their behalf.