Since the 2013 première of Daniele Abbado’s Covent Garden production of Nabucco, I’ve visited Berlin and seen the Holocaust memorial, so I now understand the equation that large collections of cuboid concrete blocks equals Holocaust. But a generic “this is about bad things happening to Jews” message is just about all that I do understand about Abbado's concept: where the Royal Opera describes his staging as “powerful”, I can only see muddle. Visually, it’s a monochrome, low-contrast affair: grey costumes on grey concrete over sand: geometrically interesting and more brightly lit than many of its ilk, but not improving on a second viewing.

There’s virtually no attempt at acting direction. The chorus does plenty of moving around, although at any given point, I am still unable to discern who is who and why they are going where they are. The main performers are almost completely static, taking up their positions and singing their stuff.

Of course, this evening was never going to be about the staging. The house was a total sell-out because of the hallowed presence on stage of Plácido Domingo. “Proper Verdi baritone” or not, Domingo confounded the critics in 2013, but three years on, could he still carry the title role? The answer was a qualified yes. Domingo still has the vocal heft to reach the Amphitheatre and he retains the ability to act with his voice. A successful Nabucco must make the transition between grandiose swagger as the scourge of the Jews in Act I to an extremely intimate portrait of a deranged old man; Domingo accomplished that transition with total credibility. His “Deh perdona” as he pleads with Abigaille to spare his daughter, was one of the highlights of the evening: here is a singer with a unique ability to touch the audience’s hearts. But this was very much a solo performance: there was so little interaction between Nabucco and the other characters that it was impossible to be fully drawn into the drama.

The audience interval chatter confirmed that the outstanding singing of the evening came from Liudmyla Monastyrska’s Abigaille. What makes Monastyrska ideal for the role is her dynamic range: when she goes for the grandiose “Salgo già del trono aurato”, you’re left in no doubt whatsoever about who, barring an Act of God, is going to come out the winner of the golden throne. Just moments before, she displayed total control of pianissimo in the contemplative “Anch'io dischiuso un giorno”. One had to forgive a number of bad lapses in coloratura and Monastyrska’s limited physical acting, but she put a lot of meaning into the words and was able to generate real thrill.

Canadian bass John Relyea doesn’t sing in London all that often, but he’s a favourite at the Met and his performance as the priest Zaccaria demonstrated why: a smooth bass voice with plenty of colour and plenty of authority. Fellow North American Jamie Barton made a promising Covent Garden début as Fenena, showing good timbre and nice control of line. Fenena and Ismaile are considerably lesser roles than the other three, but Barton and Jean-François Borras mode a good fist of them, particularly effective in ensemble.

The Royal Opera Chorus clearly love this work, particularly going for it in the big Act I choruses. To my surprise, “Va’, pensiero” was approached with less of the big swell and more subtlety: the highlight was a beautifully held fade-to-black pianissimo, ending the number with the bass notes lingering delicately. Maurizio Benini conjured a workmanlike orchestral performance: adequate without ever hitting the heights.

This Nabucco will get better during the run as the ensemble performance improves. But even with the high class singing on display last night, it will always struggle to overcome a muddled staging which fails to put across its concepts.