The great mezzo-soprano Marilyn Horne has often said, only half jokingly, that quite a few opera conductors she has worked with think that most mezzos are, in fact, just lazy sopranos.

John Relyea as an angel who watches over Jennifer Larmore in "La Cenerentola." (Jack Vartoogian for The New York Times)

Of course, however funny, the charge is unfair. Yet, at a time when a new, exciting roster of mezzo-sopranos has come along, some of them do sound like lighter lyric sopranos with clear upper registers and no particular punch in the lower voice.

Jennifer Larmore, who sang the title role in "La Cenerentola" at the Metropolitan Opera on Thursday night, the first performance of the Rossini favorite this season, is the real thing: a strong, true mezzo-soprano. What categorizes a voice is not just its range, but its color. Ms. Larmore's sound has the natural, dusky, deep coloration of a mezzo-soprano, even when she dispatches Rossinian roulades and trills, which she does with ease, and lets fly gleaming radiant top notes that many a soprano would covet.

The Met's current production of "La Cenerentola" was mounted in 1997 specifically for Cecilia Bartoli, who sings the role exquisitely. Ms. Bartoli is a perkier physical comedian than Ms. Larmore, who, true to her Georgia roots, is a more gracious, laconic stage presence. Ms. Larmore brings special qualities to the role, notably warmth and vulnerability. For all its funny business, Rossini's version of the Cinderella story is psychologically astute.

Cinderella, whose given name is Angelina, is a plucky young woman who puts up a real fight to try to convince her abusive stepfather to let her go to Prince Ramiro's ball with her snide stepsisters. And in the end, when she marries the prince, who wants to severely punish his new bride's so-called family, she pleads with him to be merciful, adding sagely, "My revenge is to forgive them." Ms. Larmore caught the resiliency and decency of her character without making Cinderella an implausible goody-goody.

The tenor Raul Gimenez, as Don Ramiro, the Prince, had some trouble with the repeated high C's in his Act II aria. But it seemed a temporary lapse; for the most part his singing was bright, clear and virile. The bass Alessandro Corbelli, as the prince's valet, Dandini, who spends most of the night disguised as his boss, provided a model of Italianate vocal style and droll comic acting. The bass Simone Alaimo as Don Magnifico, the stepfather, was sometimes too huffy-voiced but essentially sang with robust sound and energy. The soprano Joyce Guyer and the mezzo-soprano Patricia Risley were the amusingly awful stepsisters.

And in his Met debut John Relyea, a tall dashing, young bass-baritone from Ontario, brought his hearty voice and easy authority to the role of Alidoro, Ramino's adviser, who is also Cinderella's guardian angel. The audience adored him. This is the kind of Met debut fledgling singers dream about. The Italian conductor Bruno Campanella, also making his Met debut, led a buoyant performance. Some of the humor in Cesare Lievi's production, updated to the early 20th century, is dumb, as when dinner at the Prince's ball erupts into a spaghetti-tossing food fight. But, overall, this is a lively, colorful and fanciful show.