As Romeo and Juliet is a cornerstone of The Royal Ballet's repertory, you'd expect them to snap to it every time they dance Kenneth MacMillan's landmark ballet.

It's not as if they haven't had the practice - it's been in the rep pretty much non-stop since it was made in 1965 and last night's performance was the company's 421st of the ballet.

But the mainsail took a long time to hoist, with the first act decidedly so-so and little chemistry between some of the lead dancers.

The boyish camaraderie written into the steps for Romeo, Mercutio and Benvolio failed to convert, while Tamara Rojo's Juliet and Rupert Pennefather's Romeo unevenly conveyed empassioned young love.

The corps, meanwhile, weren't dancing as a company, and many of them looked under-rehearsed.

Even by an improved Act III it was only Rojo, pictured right, who was psychologically and dramatically plausible.

Her portrayal of Juliet's dilemma - her terror of the sleeping potion matched only by her terror of marrying Paris - was chillinging conveyed, as were her desperate pleas to her parents to stop the nuptials.

Jose Martin's Mercutio and Gary Avis as Tybalt did sterling work in Act II, with Jose Martin especially good in the dying scene (this can drag on).

And no complaints about Laura Morera's Harlot and Christopher Saunders as Lord Capulet, both of whom were as reliable as you could wish for.

By contrast, you suspect that Sergei Polunin, a big talent and a great looker, has been skipping class, so casual was his portrayal of Benvolio, while Pennefather's Romeo was distractingly mixed.

Pennefather, who was standing in for the injured Carlos Acosta, is an able dancer.

He also has lushly blond good looks plus a puppy-like quality that is spot-on for Romeo.

Indeed, his relative inexperience next to Rojo syncs with MacMillan's interpretation of the story.

However, his acting currently lacks the depth to carry an evening-length dance-drama.

In rep until 16 March. Information: 020 7304 4000, www.roh.org.uk.