Other celebrities among the 250 invited guests included Lyle Lovett and Sean Penn. Quite other were the Russian musicians: revered as Tchaikovsky specialists, they brought finesse, drama and soul They were the stars.Jenny Gilbert is away. The trouble with "difficult" modern dance is that it puts people off buying tickets for wonderfully digestible shows like Sasha Waltz's Impromptus. With just seven dancers, a pianist (Cristina Marton), an on-stage mezzo-soprano (Judith Simonis) and an architectural setting of three rhomboidal planes, this piece might have got lost on the huge Playhouse stage.

But instead the quiet subtlety of the movement and music had such evocative profundity, they suffused the empty spaces between with a luminous beauty The effect was riveting, the audience was transfixed. And it was all the more surprising because it was so different from what this company, Sasha Waltz & Guests, had previously shown in Edinburgh and London. The splendidly named Waltz (she got the label from her parents) is normally linked with robust dance theatre, a style that figures from someone born in Germany and working in Berlin. Her last piece here, K?r (2000), was by turns unexpected, brutal, grotesque, funny - but it was dance theatre. Impromptus (2004) is, by contrast, lyrical, gentle and dancerly It marks Waltz's debut with live classical music.

Sometimes the dancers move to silence, but otherwise they move to Schubert: five piano pieces and four lieder. Each dance has a distinct look, just as each component of the piece - visual, aural - is separate yet also interlocking. In one dance the dancers appear and disappear in a continuum of running and turning, as if swept on the rippling wind of the piano notes. Another dance focuses on semaphoring arm movements; another, a duet, on small tip-toeing steps, backwards and forwards, interrupted by prominent lifts. The performers stand on two of the tilted planes, which overlap like tectonic plates, in front of the third, vertical plane. Martin Hauk's lighting creates sculptures of geometric shadows or melancholy chiaroscuro ambiences.There is humour, too, in the squelching entry of dancers wearing water-filled gum-boots. And there is humour with the pool that opens up in the floor, inviting women to bathe, an arc of water splashing up to herald the arc of another dancer's body. But before that the mood had turned sombre, when red paint trickled down the dancers' bodies like blood.