Why are there swans in Swan Lake? Is it simply because they are lovely looking creatures and when you put ballerinas in short, white tutus and frilly, white knickers and get them to move with swan-like grace it makes for gorgeous stage pictures? Is it just a pretty fairy tale, or is there a deeper appeal?

The answer is both, and ballet companies are judged on how well they combine physical beauty with the ballet's darker themes of sex and death.

Fifty years after its first UK visit back in 1956, and many more since, the Bolshoi Ballet is dancing Swan Lake at the Opera House, and while it has no problem with beauty, it faired less well with the psychological insights.

This is unexpected, because its current production of Swan Lake is the work of Yuri Grigorovich, the former dancer and one-time Bolshoi director, who's replaced the allegorical fairy tale with more explicit psychological themes.

Swan Lake traditionally gives us the dual feminine - the virginal Odette and the vampish Odile.

With Grigorovich we also get the dual masculine: the Prince is a dutiful royal son, but also a melancholy man with what shrinks would call "conflicts".

The problem is that last night's Siegfried was just not up to the acting required. Ruslan Skvortsov did a little frowning, and a lot of sighing, but gave no real sense that he was a man in psychological crisis.

His dancing was also disappointing, with fluffed spins and low leaps. He took things very, very carefully, as you would a driving test, but nothing could help his wobbly lifts.

The coolly awesome Svetlana Zakharova was Odette/Odile, and she looked unimpressed.

Her dancing was tip-top, even if it was aimed more at the audience than her onstage love. In truth, Skvortsov and Zakharova were as suited as ham and custard - a poor pairing for a first-night cast.

Much better was the Joker/Fool character, danced by the dazzling Viacheslav Lopatin.

A very, very fine dancer, he invested this potentially comedy role with an unexpected menace. Also good was Dmitri Belogolovtsev as the Rothbart/Evil Genius character.

His moves shadow the Prince's, just as the black swan mimics the white. This double parallel is the crux of Grigorovich's Swan Lake: the Prince doesn't know himself, and he doesn't know the woman he wants.

Shame that not all the dancers were up to the theme.

• Swan Lake until 5 August, plus 16 August. The Bolshoi seasons runs until 19 August. Information 020 7304 4000.