A century ago Sergei Diaghilev launched the Ballets Russes, the crucible where modern lyric and dance theatre was born. Picasso and Matisse jostled against Nijinsky, Debussy and Markova, Satie and Cocteau against Fokine, Stravinsky and Pavlova. Tomorrow the spirit of Diaghilev is invoked in the premiere at Sadler's Wells, London, of four new dances by today’s leading choreographers.