Of the 28 young artists taking part in the Merola Opera Program this summer, only a few will be chosen to move on to the Adler fellowships, the next stage in the San Francisco Opera Center’s training program.

So let’s spare a moment of sympathy forCarrie-Ann Matheson and Markus Beam, the center’s leaders who will have to make that decision. After the incendiary demonstration of vocal talent on display Thursday, Aug. 3, during the program’s annual Schwabacher Summer Concert, I can’t imagine having to select among the great and the also great.

For two hours in the concert hall of the San Francisco Conservatory of Music, one artist after another trooped onstage to show how beautifully, how dramatically, and how expressively these operatic excerpts — by Verdi, Handel, Donizetti and more — could be delivered in the right hands.

Usually there’s at least one singer on hand who is, if not less gifted than the others, perhaps a little out of their depth. Maybe it’s a raw talent still in need of more seasoning and training.

This wasn’t one of those nights. As each scene gave way to the next, and one group of powerhouse singers handed off to another, the audience settled in for a stretch of unbroken awe and delight, with no weak links in sight.

The Schwabacher Concert is in some ways an ideal showcase for the Merola singers. Solo arias, of the sort that they perform in auditions and at the Merola Grand Finale concert (slated for Aug. 19), offer a detailed close-up of an individual artist. A full opera is a huge, collaborative undertaking.

This format, though, is devoted to extended excerpts, ranging in scale from a single duet from Handel’s “Giulio Cesare” to the entire second act of Verdi’s “Otello.” It’s a perfect compromise, offering singers a chance to shine on their own and also to interact dramatically and vocally with their peers.

Thursday’s program found these singers — a group of artists from around the world, with an unusually high international contingent this year — in good hands. The American conductor Steven White led the performance with crisp exactitude, and director Omer Ben Seadia gave all but one of the six scenes a delicate but apt theatrical touch. The exception was a duet from Donizetti’s “L’elisir d’amore,” directed with zesty comic imagination by Merola participant Tania Arazi Coambs.

If the entire evening went by on an unfailingly high note, there was nevertheless one standout contribution: Appearing as Iago in the “Otello” excerpt, Cuban baritone Eleomar Cuello gave a performance of such musical eloquence and theatrical bravura that the audience couldn’t quite believe what we were witnessing.

The core of this act, and of the entire role in the opera, is the “Credo,” Iago’s gleefully spiteful avowal of faith in a malevolent deity. Cuello sang this while perched on the lip of the stage, making terrifying eye contact with listeners in the first few rows, and shaping the aria’s musical phrases with barely disguised fury. It was a tour de force of characterization.

当其他角色their appearances — Welsh tenor Thomas Kinch as Otello and French soprano Juliette Chauvet as Desdemona, both first-rate — Cuello’s Iago reverted to his role as an obsequious sidekick. The result was a brilliant dramatic confluence featuring all three artists.

另一个Verdian三角形,从“Rigoletto”,开始了the evening superbly. Kevin Godínez, an eloquent baritone from Costa Rica, sang the title role robustly, matched with pinpoint clarity by South Korean soprano So ry Kim as Gilda. Tenor Daniel Luis Espinal was a lusty, full-voiced Duke of Mantua, and mezzo-soprano Lucy Altus brought her beautifully resonant tone all too briefly to the role of Giovanna.

The rest of the program? Also terrific.

I was floored by the expansive luster of contralto Cecelia McKinley and British soprano Joanne Evans in the Handel duet, and tickled to death by the comic high jinks of tenor Demetrious Sampson Jr. and bass-baritone Finn Sagal in the Donizetti. A duet from Ambroise Thomas’ “Hamlet” made a tender vehicle for the artistry of baritone Samuel Kidd and Chinese soprano Shan Hai, and a scene from “Silent Night,” Kevin Puts’ Pulitzer Prize-winning 2011 opera, did the same for soprano Georgiana Adams and tenor Sahel Salam.

I’m out of superlatives. Give every one of them a spot on the Adler roster.

Reach Joshua Kosman:jkosman@sfchronicle.com; Twitter:@JoshuaKosman