It was heartening to see Lisner Auditorium nearly packed Friday night, when Washington Concert Opera presented a rare performance of Rossini's "La Donna del Lago" (1819). It was even more heartening to see how many people stayed on as this beautiful but lengthy opera unfolded gradually through what proved a hot and stuffy evening.

WCO came close to folding last summer, after a couple of prestigious but very costly seasons at the Kennedy Center. Now the troupe is back at Lisner, its traditional home, which is easier to fill and more economical all down the line. I hope WCO is here to stay, for its venturesome presentation of significant but rarely heard operas is a musical and intellectual boon for the capital city. Moreover, Friday's performance offered some genuine thrills.

Because there were a number of gifted and hardworking singers in the cast, it may seem ungracious to say that tenor Lawrence Brownlee stole the show. Sorry, but there's no way around it. After all, nobody but the most fervent opera cultist remembers who sang with soprano Montserrat Caballe when she dazzled Carnegie Hall with Donizetti's "Lucrezia Borgia" in 1965; it was one of those nights when a star was born and carried all before her. Without taking the comparison too far, it is distinctly possible that Brownlee's performance on Friday may someday be remembered with some of the same fondness.

Brownlee -- who sang the role of the Scottish King James V, disguised as "Hubert" for most of the opera -- has a voice of high, brilliant, florid beauty that he employs with spectacular confidence, dexterity and musical intelligence. His pitch sense is spot-on; his coloratura flourishes are immaculately calibrated. At times, one wishes his voice were a size larger than it is -- a few stratospheric fortes sounded strained -- but he does a great deal with what he has, and combines it all with stage presence of considerable electricity. He was cheered to the rafters, and rightly so.

George Dyer, who sang the role of Roderick, is a very different sort of tenor, with a larger, more traditionally "heroic" voice, a less intense and mercurial artistry and, for the moment at least, only middling polish. Still, the fact that he was able to share a stage with Brownlee and generally hold his own speaks well for the young Dyer's promise. Soprano Irini Tsirakidis was smooth, languid and somewhat wan in the part of Elena, although she proved capable of rising to the occasion when dramatic fervor was called for. Matthew Lau boomed broadly as Douglas. Mezzo-soprano Gloria Parker, who sang the "trouser role" of Malcolm, is clearly a sensitive and conscientious musician, but she has very few notes that ring with any luster. Joseph Haughton (Serano) and Michelle T. Rice (Albina) fulfilled their duties earnestly.

WCO Artistic Director Antony Walker led the good pickup orchestra and chorus with a vibrant, appreciative sense of Rossinian style. Tune followed tune, crescendo followed crescendo, and everybody came out onstage for a finale to tell us what his character was thinking. Formulaic? To be sure -- but they are brilliant formulas, and Rossini was their absolute master; one might as well complain that Bach wrote too many fugues.

I will admit that the composer's comic operas appeal to me somewhat more than do his quasi-realistic and self-consciously serious efforts like "La Donna del Lago." This setting of Sir Walter Scott's poem "The Lady of the Lake" offers Rossini little opportunity to delve into the cracked, giddy, musical surrealism that makes him unique among all composers past and present. But it is still Rossini, and we should be grateful to WCO for allowing us to hear it. And Brownlee is a genuine find.

Lawrence Brownlee's performance in "La Donna del Lago" was one for opera fans to treasure. Irini Tsirakidis was a languid and smooth Elena.