Balanchine 100, Royal Opera House, Covent Garden

It's worth struggling through the snow for this one. 2004 is the centenary of choreographer George Balanchine's birth. The Royal Ballet's celebration is a triple bill of masterpieces: Prodigal Son, made in 1929 for Diaghilev's Ballets Russes, the astounding Agon, and Symphony in C as the perfect closing ballet.

The classicism of Agon stretches from court ballet to New York jazz. The fanfares and metres of Stravinksy's serialist score look back to the 17th century; Balanchine's steps pounce on their jazz rhythms. Movement bunches and flows through the dancers' bodies.

The Royal Ballet is now an international company, and it dances Agon in several different accents. (Conductor Paul Hoskins's sludgy rhythms don't help.) The corps of girls tend to small-scale primness. Soloists, especially those returning to the ballet, strike out more strongly. Zenaida Yanowsky is getting bolder with every Balanchine role she dances. Her account of the ballerina role had always been forceful, if a little correct. This time she's found more contrast, more scale and much more glamour in the great pas de deux. Johan Kobborg's steps, still cut- glass, are freer.

With Prodigal Son, feted ballerina Sylvie Guillem is the Siren to Carlos Acosta's Prodigal. In fact, Guillem is the evening's weakest casting.As the Siren grips the Prodigal between her thighs, their duet is sexually explicit and icily stylised. It's eroticism at its cruellest, but Guillem prettifies it. She looks overstretched by those dances - she gives full value to the sky-high legs, but skimps on weighted gestures.

Carlos Acosta is a young and rather classical Prodigal. Flinging himself against parental restraint, he can't help turning his tantrums to a smooth academic finish. His polish is so involuntary that it becomes touching, part of the Prodigal's character.

Despite Guillem, the ballet's emphatic force, its parable plainness, is still powerful.

Symphony in C is all sparkle and youthful grandeur - four ballerinas, each with cavalier and court, to Bizet's early symphony. This performance fizzed along: best in the allegro sections, especially with Laura Morera leading the country dances of the third movement. Alina Cojocaru is cavalier with the music in the first movement, but her ease of movement is lovely. The finale brings all the ballerinas, all the courts, onstage: dancer after dancer polishing steps into brightness.