On all cylinders: Leo Nucci and Nadine Sierra thrill in La Scala's classic Rigoletto

"This production was even older when it came out in 1994," quipped one audience member during the interval. From its period setting to its grand, towering sets, Gilbert Deflo's take on Rigoletto - now in its eighth run at La Scala - is as traditional as it gets in the contemporary age of experimental opera. That in itself is far from problematic: many envisage La Scala as a bastion of high-end traditionalism, and those who flock to its shores for a taste of precisely that got what they expected tonight. Flare in the casting department combined fresh talent with an old hand, making this time-honoured production gleam anew.

House debutant Nadine Sierra and veteran Leo Nucci made for a triumphant partnership. At the end of Act II, their duet "Si, vendetta" pushed house excitement beyond the point of no return, prompting cries of "Encore!" to rain down from the gods amidst a smattering of resistant hisses. A moratorium on aria repeats has existed since the time of Toscanini (daringly breached on only a handful of occasions, most notably in the Muti era), and musicians looked uncertain in a house that does not wear its heritage lightly. Nucci's searching gaze sought consent from Sovrintendente Alexander Pereira (stationed ready for action in a box stage right), who joined the applause to signal his approval. The encore went ahead, and journalists scrambled for their Twitter apps. So ecstatically received was this leading duo that it brought into being the next chapter of La Scala legend.

Nadine Sierra is the Gilda currently on everyone's lips. Her Metroplitcan Opera debut in the role last December had the New York Times proclaim her discovery of the season. Tonight's was a butter-wouldn't-melt-in-her-mouth reading of Gilda, where Sierra's lissome form and girlish looks felt particularly well-suited to a role that fits her like a glove. The voice is peachy and sun-drenched, and it glides through Verdi's mellifluous lines with a gratifying purr. Confirmation of her abilities came with "Caro nome": all chirruping trills and wax and wane, with Sierra jumping off high perches to trickle down her even range. This was a triumphant La Scala debut for the 27-year-old in what she acknowledges as her favourite role.

What makes Rigoletto just about everybody else's favourite role? That surely has something to do with the character's dramatic depth, where a decent reading can move us from disgust to empathy within the space a single aria. There is none better than Leo Nucci for this towering role – the visceral animal of the stage has over 500 performances of the role under his belt, and, at the age of 73, Nucci now eats this operatic challenge for breakfast. Physically, he is a sensation, limping about the stage carte blanche, his eyes lighting up with expressionistic terror atop delirium tremens hands. Vocally, he retains his heft, his rich, nutty core now clad in a gruffness around the edges that lends extra bitterness to this characterisation. When this baritone is on the stage, it is impossible to take your eyes off him. "Cortigiani vil razza dannata" was a masterclass in high drama, with Nucci oozing magnetism from every pore.

Whilst Nucci was thrillingly unpredictable, the untempered bravado of Vittorio Grigolo seldom comes as a surprise. Nevertheless, this was a piece of strong type-casting: a red-blooded Duke full of rollicking tenacity. Annalisa Stroppa's Maddalena was full-bodied and bawdy, whilst the dark bass of Carlo Colombara made for a tenebrous Sparafucile with long straggly hair. On fine form throughout, the chorus displayed characteristic verve as courtesans in licking dialogue, torchlit kidnappers and a howling evocation of Act III's thunder.

Act I's Mantuan court drips with luxury, from gold-lacquered columns and marble floor to the period finery of Franca Squarciapino's costumes: noblewomen in floral pinks and blues, plume-hatted noblemen and revellers topped with ruffs. Long pauses between gargantuan set changes lead the momentum to lull, though ennui is forgotten when our eyes meet the red-brick exterior of a Renaissance palazzo as seen from the alleyway of Act I's second scene. In a rare stray from the libretto, Act III offers a towering warehouse edifice fronted by a gaping open space (instead of the usual glimpse into Sparafucile's house through two windows). Here, Gilda roams vulnerably, spied on by her eventual killers rather than visa-versa as the plot conventionally suggests.

Finnish conductor Mikko Franck, originally billed for this production, was inexplicably replaced by Nicola Luisotti, thus placing on the podium an unquestioned purveyor of italianità. His was a full-throttle account, where driving gestures produced strong forward momentum amongst moments of breezy spaciousness. Verdi's phrases are laden with fast-shifting moods, and Luisotti would reel the steering wheel before applying the throttle. This is a Rigoletto that runs on all-cylinders, and the old classic shows no signs of slowing down.