After a disappointing Romeo and Juliet last week, the Mariinsky set all to rights with Swan Lake. The Tchaikovsky biggie is why we revere the St Petersburg troupe. It dances it with more seriousness and more finesse than anyone else, its corps of swans in perfect unison and its belief in the story complete.

Even very good ballet companies can be seen rather knocking off the steps but for the Mariinsky they are a kind of pilgrimage, and in the process are transformative for us.

Its belief is in the details. The corps is not just a line-up of pretty girls (though that they are) but also a hypnotising nimbus for Odette; the Tutor and Jester are not only roles for an older dancer and a whiz-bang young one but also reminders of the Prince’s conflict between high learning and high jinks, something he must reconcile; and Odette and Odile are not two fancy roles for a ballerina but two aspects of the feminine that must also be resolved.

This being the Mariinsky, we judge on much tighter standards than lesser troupes. No doubts about its corps of swan, nor the national dances in the Ballroom scene, nor the Act I pas de trois.

The Jester (Andrei Ivanov) was also excellent, his virtuoso moves and believable acting proving the role doesn’t have to be the panto it usually is. Also good was Ilya Kuznetsov as Von Rothbart. The evil magician is often portrayed as a creaky malcontent but with Kuznetsov he’s a sexy adventurer.

As Odette, Uliana Lopatkina was trance-like. Some pick at her quirky interpretation, and what could be a sharper Odile, but for me her tranquility is mesmerising. As her Prince, Daniil Korsuntsev was smooth dignity.

Swan Lake until 11 August. Mariinsky season until 15 August. Information: 020 7304 4000, www.roh.org.uk