From one of the last overlooked corners of opera’s past – opera comique, the irreverent answer to the lavish Baroque court music of Lully and Rameau – the American Symphony Orchestra has unearthed a jewel. Emmanuel Chabrier’s “Le roi malgre lui” (“The King in Spite of Himself”) is a sarcastic, extravagant, romantic treat.

Even in France, this work is seldom staged, more often given in concert form (as it was here). Despite good reviews and appreciative audiences, it has failed since its 1887 Paris premiere to find a regular place in the operatic repertory. Judging from Sunday’s spirited performance and the audience’s roar of delight at the conclusion, “Le roi’s” time has come.

Nowadays we’ve gotten used to opera being grand and serious. Opera comique, which flourished until the end of the 19th century, thrived on shirking profundity in favor of exotic settings, spectacular effects, grisly melodrama, and take-no-prisoners satire. It’s an art that, even at its heights, never took itself seriously; Wagner couldn’t have written one.

“Le roi malgre lui” tells the convoluted, slightly daffy comedic tale of an attempt to assassinate Henri III of Poland, a 16th-century French king unhappily reigning at Krakow. The king is mistaken for a courtier and invited to join the assassins, a development he accepts with appropriately French irony. While this improbable situation goes on its absurd way, utterly gorgeous music – much of it anticipating the splendors that made 20th century France a musical glory (Debussy, Ravel, Poulenc, even a little Messiaen can be heard taking initial breaths in Chabrier’s notes) – completely ravishes the ear.

The ASO made a triumphant case for Chabrier’s work in spite of a few setbacks. Avery Fisher Hall’s acoustics do not favor solo voices, and Chabrier’s Wagnerian-size orchestra is not easy to sing around, anyway. Conductor Leon Botstein drew stunning moments of beauty from his instrumentalists, but he sometimes swamped his singers (even the excellent Concert Chorale, led by James Bagwell), and at times the ungainly, unpredictable whole proved beyond his control.

This opera probably needs a genius of a director to consolidate. But Mr. Botstein’s obvious passion for “Le roi malgre lui” paid off, especially in his selection and rehearsing of the singers. A few weeks ago, Patricia Petibon, in L’Opera Francais de New York’s “Pelleas et Melisande,” was haunting and unforgettable as that opera’s doomed heroine. Sunday, she played a ditzy slave girl whose love for a nobleman generates comedy, near-tragedy, and triumph.

Ms. Petibon is already a star in France; after a performance like this one it would be bizarre of New York not to fall for her as well. Her lithe soprano has deepened since her years with the Baroque ensemble Les Arts Florissants; instead of a merry coloratura sprite, Ms. Petibon has become a lyric leading lady. She takes the stage and dominates it blissfully. A few soft high notes went awry, but they didn’t hinder her obvious success.

In the last-act duet, Ms. Petibon and Philippe Castagner, who for two acts had been the opera’s comic foils, suddenly grew into grand, romantic figures. Both made the switch not improbable but enchanting. Mr. Castagner is one of the most promising tenors since the late Alfredo Kraus. The manner is fresh, appealing, and winning, the voice saucy, wide-ranging, flexible. At first it sounds too light for serious moments – but then he opens it up and his voice soars and crests beautifully.

It was moving to see a few operatic old-timers rush to the footlights (like people used to do more often) to cheer the young singer. They were on to something: with luck and the right opportunities, Mr. Castagner could be a major tenor of his generation.

Twyla Robinson, as a crafty former mistress of the king’s, has an appealing soprano and witty acting skills. As Henri, the fine baritone John Packard seemed unsure of just how to behave in the comedic surroundings, and after a lovely entrance aria, not all his singing was affecting. Andrew Schroeder got laughs but went too often for contemporary shtick. In other roles, Scott Williamson, Brian Dougherty, Andrew Martens, Andrew Nolen, and Frank Ream all sang and acted quite well.

The occasion’s true stars, however, were Chabrier and “Le roi” itself. With its antic spirit, shameless adeptness at parody in one moment (right in the middle of an aria, Chabrier steals a hilarious orchestral quote from Berlioz’s “Damnation of Faust”), and heartbreak in the next – as well as astonishingly rich and imaginative orchestral writing and demanding but always rewarding vocals, “Le roi malgre lui” is a smash hit in spite of its past, and a smart opera company would stage it as soon as possible.