First Night: Tosca, Royal Opera House, London

The scene was set, the seconds were out and, with Puccini's thunderous Scarpia chords sounding their prophecy of doom, the battle was joined: not only between good and evil, tyranny and freedom, but between other opponents as well.

Director-designer Franco Zeffirelli's super-realistic production, which had held sway at Covent Garden for 42 years, was being replaced by a new staging by director Jonathan Kent and designer Paul Brown.

Meanwhile Maria Callas - Zeffirelli's Tosca and still for many people synonymous with the role - is being challenged by Angela Gheorghiu.

Tension was high, as rehearsals for this show have been as shrouded in secrecy as were those for the opera's première in 1900, with the inevitable diva stories doing the rounds: "More interested in choosing her jewels than attending rehearsals" being the bitchiest crack at the demanding Romanian.

But when Gheorghiu makes her entrance, bringing flowers to the Virgin, it's as a sweetly vulnerable girl: her voice has that self-mocking lightness which precedes any knowledge of life's darker side. And she's very much in love, launching into her opening duet with Cavaradossi - Argentinian tenor Marcelo Alvarez - she can barely keep her hands off him and when she begins her daydream aria about the cottage they will inhabit, the stage seems suffused in light.

But with its gates and bars, this church of Sant'Andrea della Valle is more like a prison than Zeffirelli's was, and when Bryn Terfel makes his entrance as the police-chief Scarpia, evil comes home to roost.

And Terfel is surprisingly good casting: vain, composed, and perfectly relaxed, he positively radiates menace and, when his eye lights on Gheorghiu, simmering lust. As he infects her mind with the poison of jealousy, his insinuating timbre sparks her anguished aria in which all the vocal glory we have come to expect from her is fully on display.

Act Two, in which Tosca and Scarpia play out their mortal duel, is handled absolutely straight, with the torture element kept in balance (no trace of the programme notes' trendy nod towards Abu Ghraib).

While the conductor, Antonio Pappano, brings out Puccini's exquisite blend of tenderness and cruelty, and sensitively explores his multiple musical perspectives - the offstage choir, the bells, the distant band - Gheorghiu and Terfel stalk each other in a deftly choreographed contest. She is by turns terrified and murderous, at one point ready to brain him with a brass candlestick, at others cowering. When he makes his final lunge, and she turns on him and stabs him, the physicality of the event is a shock. It feels appropriate that before turning away she tears the cross from her bosom and throws it on his corpse in horror.

The beautifully-designed final act unfolds with all the requisite inevitability: the shepherd boy sounding bucolic, Alvarez's farewell aria touching the heart, the excited planning by the lovers, the ghastly denouement. So who's won? Well, I will happily trade Callas for Gheorghiu in this role, and Kent and Brown have pulled off what seemed impossible. Bravo.