Metropolitan Opera, Marty Sohl, Associated Press
In this photo provided by the Metropolitan Opera, Stephanie Blythe performs as Amneris in Verdi's "Aida" during a dress rehearsal at the Metropolitan Opera in New York City on February 2, 2012.

NEW YORK — In 1872, a dissatisfied opera-goer who had attended a performance of Verdi's "Aida" in Parma, Italy, wrote to the composer asking for his money back. Amused by the man's audacity, Verdi complied.

If no one in the Metropolitan Opera audience Thursday night had a similar impulse to seek a refund, there's one main reason: Stephanie Blythe.

The great American mezzo-soprano was singing the role of Amneris for the first time in the house, and she single-handedly elevated a mediocre performance into a memorable night at the opera.

Though the Ethiopian slave Aida gets the title role, the far more interesting character is Amneris, the Egyptian princess who competes for the love of the soldier Radames. Aida is basically a suffering victim, while Amneris comes to realize the tragedy her jealousy has unleashed.

With her lustrous, force-of-nature-size voice, Blythe conveyed Amneris' pride and imperiousness with ease, but she also captured her more vulnerable side in introspective moments.

While she has excelled in a variety of roles at the Met, the glory of Blythe's voice lies in its plush lower and middle register, and she lacks the easy top notes of a classic Verdi mezzo. Once or twice she landed ever-so-slightly flat, but in the Judgment Scene, when it counted most, she punched out the B-flats and numerous A-naturals with dead-on accuracy and stinging power.

Blythe also brought uncommon acting skills to her portrayal, inhabiting the character through regal gestures and unguarded reactions. Alone among the principals, she apparently had not gotten the memo that, in this grandest of grand operas, singers should employ the "park and bark" technique of simply standing on stage and belting out the vocal line.

Sadly, even their belting was not impressive. As Aida, soprano Violeta Urmana struggled in the Nile Scene, running out of breath near the end of "O patria mia" and skipping a phrase entirely later in the act. Tenor Marcelo Alvarez gasped his way through "Celeste Aida" and after that sang either at maximum volume or in a hoarse whisper. As Aida's father, Lado Ataneli bellowed in a dry, unattractive baritone. Veteran bass James Morris brought dignity and a slight wobble to the role of the high priest Ramfis.

At least the chorus and orchestra, conducted by Marco Armiliato, were in top form. And, for Blythe, it was a triumph.