Star power is a remarkable thing. Gluck’s “Iphigenie en Tauride” is hardly one of opera’s greatest hits. And in the Washington National Opera’s production of it, which opened Friday night, there are a lot of other singers on stage besides Placido Domingo. Yet when Domingo, in the role of Oreste, shackled, imprisoned and demoralized, sang his very first line, it was clear not only whom the crowds at the Kennedy Center Opera House had come to see, but why they had come to see him.

No one would claim Domingo, 70, is in the vocal condition he was as a 35-year-old. But the quality of the voice remains: the golden tone, the ping to the sound, even, perhaps, the long habit of being the center of onstage attention. Amid all the other singers, he made you want to listen to him. When the aging Pavarotti came on stage, it was as a mere husk of his former self; Domingo in his late years, by contrast, keeps finding new vessels in which to present the essence of who he has always been. Certainly, this entails vocal and musical adjustments (in “Iphigenie,” Domingo combines the baritone and tenor versions of the role). But he’s still genuinely got something to offer — more than many others today.

This “Iphigenie,” which he has also been singing at the Metropolitan Opera this year, is a savvy repertory choice. The Cliffs Notes tag for this opera is “reform”: Gluck sought to strip away the florid vocal excesses of Baroque opera, the long arias with lots of runs and trills and repeated words, and present a more solid form of genuine sung drama. In his penultimate opera (written in 1779, revised in 1781), dialogue and recitative have the same weight — and the same orchestral accompaniment — as the arias, and the music is straightforward, without a lot of harmonic complexity. Effective drama and beautiful music without vocal acrobatics: It’s a good fit for a 70-year-old tenor.

Domingo also gets to play a lead role while someone else does even more heavy lifting. As Iphigenie, the soprano Patricia Racette is on stage most of the night, from the moment the curtain rises on a dire storm scene executed in shades of black and gray (Emilio Sagi’s production and Luis Antonio Suarez’s sets, originally from Oviedo, Spain, hew to what has become a fairly conventional form of metal-colored, bare-staged abstraction). Iphigenie, the priestess of the temple of Diana, stands high atop a single jutting, prow-like protuberance at one side of the stage, while the bodies of the female chorus form a kind of wave, piling up against the opposite wall below her.

The soprano starts singing full throttle and keeps it up for an impassioned evening: Iphigenie fails to recognize her brother, delivered to her as a prisoner, but quails at the thought of sacrificing him (she and the chorus donned red gloves at this juncture, adding a touch of blood to the final act). Racette sings with an integrity, intense as a cold flame, that fits Gluck well. Her voice sounded foggy at first, and her high notes sometimes thinned out and fell a little short of the pitch — a questionable augury for her WNO “Tosca” in the fall — but she sang without flagging, indeed gaining, if anything, in vocal authority.

Two worthy singers and a good opera are enough to make a fine evening. You don’t need excellent conducting — William Lacey’s was serviceable, but there were ragged moments from the orchestra — or strong supporting singers. Simone Alberghini, as the evil king Thoas (who wants the prisoners sacrificed), blustered about the stage with a thick voice he kept planting in between the pitches. Shawn Mathey as Pylade (Oreste’s dear friend and fellow captive) started out with the nasal constricted sound that French diction causes in so many singers, but was able to limber up the sound into something more malleable by the end, ultimately acquitting himself with honor.

Several singers from WNO’s Domingo-Cafritz young artist training program made a good showing in small parts. Jegyung Yang stood out as the First Priestess. Javier Arrey got in a solid line or two as a Scythian. Jennifer Lynn Waters, in her third year with the program, got to wield her striking, large, metallic voice from the balcony (where many in the audience couldn’t see her) as the goddess Diana, demanding an end to such sacrifices.

There was no sacrifice for Domingo. Not only was his character spared at the end of the opera, but the singer didn’t even schedule in a break after the show. The very next day, there was a rehearsal for “Don Pasquale” before the annual Opera Ball, held in his honor. Chalk up another one for star power.

Iphigenie en Tauride

Performances continue at WNO through May 28. On May 29, PBS will air the Metropolitan Opera’s production, starring Domingo and Susan Graham.