Pietro Mascagni's "Cavalleria Rusticana," one act and about 75 minutes long, is just a little too short to make an evening of opera in itself, and so it is regularly teamed with another brief work, Ruggero Leoncavallo's "I Pagliacci." Indeed, the two have become so closely associated that they are collectively known as "Cav/Pag" in opera circles.

Washington Concert Opera decided to do things somewhat differently on Sunday night at Lisner Auditorium. Instead of "Cav/Pag," we heard "Cav/Tab," with Mascagni's hit yoked to one of Giacomo Puccini's lesser-known works, "Il Tabarro."

"Il Tabarro" ("The Cloak") is part of "Il Trittico," a trilogy of Puccini one-acters that received its premiere at the Metropolitan Opera in 1918. (The other two works are "Suor Angelica," a rather dreary soap set in a nunnery, and the sparkling "Gianni Schicchi," the composer's best comedy, which has gone on to a life of its own.) "Il Tabarro" is a blunt, brutal 45-minute study of love, betrayal and murder on a grimy Parisian barge. Although it contains some of Puccini's most sophisticated harmonies, as well as juicy parts for soprano, tenor and baritone, "Il Tabarro" has little charm and is more often admired by scholars than loved by audiences.

Sunday's performance was notable for the fiercely emotive and often very exciting singing of soprano Yali-Marie Williams, who played the role of Giorgetta. Anooshah Golesorkhi sang the part of Giorgetta's husband, Michele, in a healthy and expressive baritone voice, imbuing the character with a mixture of sorrow and cynicism. Stephen O'Mara, as Luigi, showed off a generally warm and attractive tenor voice that tended to sound strained in heroic passages.

It was artistic director Antony Walker who stole the show -- both shows, in fact. He has assembled an excellent small orchestra and chorus that are capable of surprising lushness; his leadership is inevitably vigorous, exacting and proportionate. He built "Cavalleria Rusticana" as one long tone poem. I'm always surprised by the sheer vitality of Mascagni's score, charged with a near-journalistic immediacy and emotional potency that the composer could never quite recapture, even though he lived on for another 56 years. (It has proven hugely influential: Every note in the soundtrack to the "Godfather" films derives from "Cavalleria" -- and the opera itself figures at the end of "The Godfather: Part III.")

O'Mara's strengths and weaknesses remained apparent as he took on the role of Mascagni's roguish hero Turiddu. Golesorkhi made a vivid Alfio, singing just a bit sharp here and there, losing his woman to and then stabbing O'Mara for the second time in the course of an evening. Elizabeth Bishop has a large, healthy and well-modulated mezzo-soprano voice; if she sometimes seemed too fundamentally sensible to play the wild-eyed Santuzza, it would be hard to fault her singing. Audrey Babcock was a smoldering Lola.

There was worthy support from Laura Zuiderveen (a stoical Mamma Lucia) and, in the Puccini, from Peter Burroughs, James Shaffran, Vijay Ghosh, Joy Stevans and Giancarlo Baci.

Anooshah Golesorkhi put his expressive baritone to good use in "Cavalleria Rusticana" and "Il Tabarro."