First Night: Simon Boccanegra, Royal Opera House, London

Crowning glory for triumphant Domingo

I can't remember a more anxiously expectant atmosphere than the one which gripped the auditorium of Covent Garden last night. Everyone loves Placido Domingo, everyone wishes him the speediest recovery from the cancer operation which briefly felled him four months ago. This 69-year-old's perennial mantra "If I rest, I rust" perfectly encapsulates his attitude to work: he never lets his audience down.

Dominated by deep male voices, Simon Boccanegra is a dark masterpiece by Verdi which Domingo has long championed, and its subject matter – political intrigue in medieval Italy, consanguinity lost and found – creates a uniquely dramatic brew. Thirteen years ago he sang its tenor lead at Covent Garden, but now, with his high notes largely gone, he's cast himself in the baritone title role, as the pirate-turned-monarch dedicated to resolving Genoa's feuds. He gets no conventional arias in this opera, but every note he sings must reflect hard-won wisdom, and the pain of separation from his mysteriously abducted child.

But the curtain rises on a prologue which belongs less to Domingo than to the Italian bass Ferruccio Furlanetto, who incarnates Boccanegra's sworn enemy Fiesco. Stalking each other through the opera, these titanic antagonists must be a match both vocally and dramatically, and in Furlanetto Domingo has his ideal foil. The first moment Domingo gets to make his mark comes with the aria "Del mar sul lido", in which he recounts the loss of his child. Here he brings grief rather than the usual wistfulness, and – vis a vis Furlanetto's awesome basso profundo – he still comes across as a tenor, with his old gilded expressiveness and nobility of tone. And his movements are lithe and youthful – every inch a buccaneer. As the scene winds to its agonising climax – with his simultaneous discovery of the death of his wife and his acclamation as Doge of Genoa – he asserts baleful authority.

The action then jumps forward 25 years, and he becomes transformed: now he has the demeanour of a king worn down by office. The unfolding revelations of the second act, with the lustrous Marina Poplavskaya as his long-lost daughter, and the vibrant Maltese tenor Joseph Calleja as her lover, become a drama ennobled by the sheer goodness Domingo projects. In the great council scene he becomes the voice of peace, stilling an angry mob, then pronounces a thunderous curse on the former ally who will kill him.

As the plot winds towards its terrible denouement – of retribution, reconciliation, and the passing on of the torch – it is clear that there are three heroes in this production: Calleja, Furlannetto and Domingo – with Domingo wearing the crown. Stumbling and struggling to breathe as the poison in his veins takes hold, his leave-taking wrings the heart, with his last words sounding like a benediction from the grave. Long may he continue to triumph.