Where were we? Wagner’s “Ring of the Nibelung” is unfolding at the Metropolitan Opera House. In residence is not a local company, but one from St. Petersburg: the Kirov Opera of the Mariinsky Theater, under its longtime leader, Valery Gergiev. We had seen the first two installments of the cycle: “Das Rheingold” and “Die Walküre.” On Wednesday night , we had the third , “Siegfried.”

The title role is for tenor, and it is one of the most demanding and punishing in the entire repertory. A tenor who can sing the role is practically worth his weight in gold. Earlier this week, I noted that Brünnhildes don’t grow on trees. If anything, Siegfrieds are scarcer. And the Kirov had a good and interesting one in Leonid Zakhozhaev.

Mr. Zakhozhaev showed a lovely voice, which is a strange thing to say about a Siegfried: that he has a lovely voice. Usually our Siegfrieds are rough-and-ready. Many years ago, when Plácido Domingo started singing a few Wagner roles, some of us commented: “This is bel canto Wagner.” Mr. Zakhozhaev brought a little of that too. And sometimes he sounded as much like Rodolfo (from “La Bohème”) as Siegfried.

He sang beautifully and lyrically, with hardly any straining, and certainly no barking. Of course, there was a trade-off: Mr. Zakhozhaev lacked the heft that we ideally want in a Siegfried. But he provided plenty of compensation. He held out, too, in this long, long part. From about 6 o’clock, when the opera began, to about 10:30, he was fresh as a daisy. Only in the last half-hour did he flag, faltering a bit in the middle and lower registers.

Furthermore, Mr. Zakhozhaev looked like the Siegfried of Wagner’s imagining: young, exuberant, and irrepressible. He even did some laps — sprints — around the stage. And he was gotten up rather like a Teutonic Tarzan. Rarely is a Siegfried believable, visually, but Mr. Zakhozhaevwas. And you have to admit that Siegfried is a fine specimen, for the son of twins.

Mr. Gergiev was first-rate, especially in Act I. The opera began with the kind of tension that this conductor is unsurpassed at bringing out. And this score is one of the most magical and wizardly that Wagner ever wrote — in other words, made for Mr. Gergiev (when he is at the top of his game). When the dragon stirred, you stirred, too. When the characters spoke of fear, the fear was palpable. When the forest murmured — boy, did it murmur. Etc.

Throughout most of the evening, the score was absolutely alive, with no dullness, no dragging. That is a huge achievement.

Of course, there were scattered problems. At the conclusion of Act I — one of the greatest climaxes in Wagner, and in music — the orchestra sort of went off the rails. Too bad. And the forging music was a little … tinkly. What was Siegfried repairing? The mighty sword Nothung or a butter knife? Elsewhere, some orchestral attacks were imprecise.

But Mr. Gergiev is a big-picture man, and the big picture on Wednesday night was thoroughly admirable.

In the orchestra, the horn playing stood out — it was confident, unstumbling, and musical. And from the cellos we heard the kind of playing always described as “ravishing.”

The tenor Vasily Gorshkov had made a superb Loge in “Das Rheingold” — and he was a superb Mime in “Siegfried.” He was vivid, both in his singing and in his acting. Mr. Gorshkov gave us all the characterization we need — but he did not neglect to sing accurately, even beautifully and ringingly. Not always do you get this from the “crafty dwarf,” as Wotan calls Mime.

Incidentally, the Mime in this “Siegfried” looks something like Shrek, though not green.

Another crafty dwarf was Victor Chernomortsev, the baritone portraying Alberich. He summoned considerable operatic wiles. And Wotan — called the Wanderer in “Siegfried” — was portrayed by Evgeny Nikitin, a bass. Early on, Mr. Nikitin seemed a little underpowered, and short on majesty. But he never forced matters, and he got better in the course of the opera. Never was he less than professional.

Our Forest Bird was the soprano Anastasia Kalagina, and you have heard prettier — and birdier — but Ms. Kalagina did her job. Fafner, who happens to be a dragon in this opera, was sung by the bass Gennady Bezzubenkov. You have heard grander and more imposing — but he, too, did his job.

Very much doing her job was Zlata Bulycheva, the mezzo-soprano singing Erda. I had reservations about her in last week’s “Das Rheingold” — but not in “Siegfried.” From the moment she opened her mouth, she commanded attention. She was alluring, mysterious, and beyond-human. Also, she showed a vocal power that can pop out at you.

Finishing up the show, with Siegfried, was the Brünnhilde of Olga Sergeeva. She started uncertainly but soon gained her stride. She was more touching than she was clean and exemplary — but that’s okay. And she gave the public a few satisfying Cs, including the note on which the opera ended.

How about the production? When the curtain came up, at 6 o’clock, a man near me said to his wife, “There they are.” He meant the three gigantic figures that have loomed all over the Kirov “Ring.” Who are they, or what are they? Beats me — but they make a good, or at least a steady, topic for intermission talk.

The dragon in “Siegfried” is simple — even crude — but kind of cool-looking. In “Das Rheingold,” Erda looks like an oil slick, with a very large horizontal structure on her head. In “Siegfried,” she is draped in red, with another very large horizontal structure on her head. What will happen in the concluding opera, “Götterdämmerung”? Will the three big guys, who loom over everything, burn up? Stay tuned.