The buzz backstage at the Royal Opera House in Covent Garden, Central London, is quite unlike that of any normal day of rehearsals. Amid the Tannoy calls for performers to rehearse Act II of La Bohème, giant dragon masks and rocks encrusted with Buddha heads are being wheeled to the back area, with grumpy French make-up artists flinging open black boxes and declaring that the prosthetic materials “ne sont pas arrivés!”. As more wardrobe boxes are opened, revealing garish shrimp soldier heads, rubber pig masks and an oversized red starfish, my son Humphrey and I feel as if we have stumbled on to the set of Spinal Tap, and not the tutu-led order and precision of the Royal Opera. Elsewhere in the calm corridors, the dancers are practising their pas de deux and the seamstresses are quietly running their machines, but over here in this corner it is as if the circus has come to town. Which, in a way, it has.

We are here, my 11-year-old son and I, to soak up the vibe surrounding the opening in London of an extraordinary multimedia event - Monkey: Journey to the West - the lauded Chinese opera created over two years by Damon Albarn, of Blur, and the Gorrillaz graphic artist Jamie Hewlett and directed by the Chinese director Chen Shi-Zheng. Normally I can't get my pre-teenage son out of bed before 11am in the holidays, but today I have been tripping over the pavements in Covent Garden as he rushes me to the stage door.

Whoever thought opera would be this cool, I think, as I stumble into the foyer behind him. Among the wardrobe staff, he flicks excitedly through the rails holding the 65-odd costumes designed by Hewlett, a riot of green, orange and white latex with feathers and rubber made for tiny Chinese acrobats.

“Please can I just try on that dragon head?” he asks the costume supervisor Sophie Doncaster. “OK, then,” she relents, caught between the Gallic grump behind her and the childish enthusiasm in front. “Just be careful of the wire inside; this one was made in China. Just look at all that intricate work inside.” After several minutes of working the jaw to bite everything around him, he casts it aside in favour of the feathery crane outfit.

As the latex slides on, he immediately strikes a martial arts pose - hands lifted by his head and one foot in the air. “You realise that is actually the pose of the crane that he's doing,” shouts a wardrobe assistant from the back. Humphrey starts making kung-fu sounds as he jumps around the room in it, and I can see we are in for a long day.

There is no doubt that the decision of the chief executive, Tony Hall, to stage Monkey: Journey to the West, originally commissioned for the Manchester International Festival, is a great move. The main ROH stage is more closely associated with the comforting classical perfection of Kenneth MacMillan, not an anarchic mix of acrobatics, martial arts and animation by zombie flesh-eaters, served up with a classical score by Albarn. I have twice been almost ejected from the ROH for rustling a bag and sitting a child on my lap; how on earth is that fierce crowd going to react to Albarn's invented instrument the klaxophone, parping out the sounds of noisy car horns on a typical Chinese street?

Hall is confident that this end-of-summer season is the best time for putting on something “very ambitious and exciting to see on stage”. And the opera arrives after a universally acclaimed global tour that took in opera houses in Paris, China and the US.

Certainly Humphrey, a fan of Gorillaz, didn't recognise the ROH from its red-velvet matinee of Cinderella. Hats off to them for taking on something completely new. And feel free to put your children on your lap to watch it. This time, no one will notice.

Monkey: Journey to the West is at the Royal Opera House, July 23-26. www.roh.org.uk, 020-7304 4000

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