Both Sitting Duet, Clore Studio, Royal Opera House, London

Pick it up, dust it down and see if it can still sell tickets

"Boy loves girl, girl captured by bad man, girl restored to boy by god" was Frederick Ashton's summary of Sylvia, his second full-length ballet - hardly compelling reason for the Royal Ballet to break its neck to revive the piece half a century later. What's more, this long-forgotten vehicle for Margot Fonteyn struck audiences as old-fashioned even in 1952. Pinched by post-war rationing, ballet fans craved modern glamour. What they got in Sylvia was a 19th-century pastiche complete with nymphs drinking from painted pools and firing toy arrows from bits of elastic.

Daft plot, dodgy reception, and hardly anyone left alive who remembers it... so why revive Sylvia now? One reason is that the Ashton style risks being lost to the current generation of dancers. Another reason is Darcey Bussell. Newly returned from her second maternity leave, the company's longest-serving current principal and most athletic beauty is on resplendent form - but for how much longer? Add the incentive of Zenaida Yanowsky and Marianela Nunez in alternate casts, and you have a crack trio of Sylvias such as a company is rarely able to muster.

This ballet belongs to its ballerina, and it's a marathon test of her stamina and technique. Bussell breezes through the twiddlier steps despite being taller than Fonteyn, and looks positively heroic in Act I's fresh-air poses and soaring leaps devised to show Sylvia's power as a huntress. Where Bussell doesn't quite convince is in the emotional range of the role. Sultry seductress she isn't, and the middle act, where Sylvia fakes compliance with her abductor, is the weakest. Bussell's authority returns in Act III when Sylvia assumes a princessy air and Ashton's choreography references Petipa's. There's even a Sleeping Beauty-like wedding divertissement, including a duet for a pair of goats. In all, it amounts to a brimming eyeful of decorative solo dancing, which, for Darcey fans, is a treat.

Elsewhere, the pleasures are flimsier. Jonathan Cope's Aminta partners well but uninspiringly; Martin Harvey's Eros stands miraculously still for half an act as a statue; Thiago Soares threatens sexily but all too briefly as the villain Orion. Delibes' score, under Graham Bond, is as pretty as one remembers it (prime Classic FM territory, this), and the original Ironside brothers' sets - all painted billowy clouds and classical ruins - have been sensitively restored. Biggest credit, though, must go to Christopher Newton, the ex-ballet master who pieced the steps together from scraps of sketches and old dancers' memories. As a labour of love, Sylvia is a major achievement. As dance history, it's intriguing. In the end, though, it's ticket-buyers who'll decide if it was worth it.

Upstairs from the main house, in the Clore Studio, Sylvia's antique charms find their polar opposite in a spare, near-silent performance by two bald men in baggy jeans. Both Sitting Duet is what it says - a work involving two performers, two chairs, a score, and no audible music. The prospect seems grim until you see the potential for humour. It's of the dry sort, certainly, but there's plenty of it.

Both Sitting Duet arose from the mutual desire of choreographer Jonathan Burrows and composer Matteo Fargion to create something together on equal terms. Burrows doesn't read music. Fargion doesn't dance. But in this droll two-hander they transcribe a piece of modernist music into a fantastical gestural aria, note for note, bar for bar, and it's riveting. Deriving motifs from the nervous tics performers present before going on stage - flicking imaginary dust, flexing elbows, and a complicated kneading thing that is no doubt the secret of strudel pastry - their neat visual parallel becomes something else again: a subtle, rhythmic symphony of pianissimo sounds - the whoosh of palms on denim, the click of fingernail on shoe leather, and, even, occasionally, the stifled yelp of one of them getting it wrong. Seeing is believing, and hearing, in some peculiar way, set my nerve ends dancing in sympathy.

jenny.gilbert@independent.co.uk

'Both Sitting Duet': Clore Studio, Royal Opera House, London WC2 (020 7304 4000), 17 to 19, 24 to 26 Nov