In the days leading up to the big event, several people asked me, “So, are you going to the Anna Netrebko concert?” They could be forgiven: Wednesday night’s concert at Carnegie Hall was a joint showcase for Anna Netrebko and Dmitri Hvorostovsky. She is the starry, glamorous Russian soprano; he is the starry, glamorous Russian baritone. But Ms. Netrebko is the hottest thing in opera right now: So the concert, in many minds, was “the Anna Netrebko concert.” Plus, the lady was making her Carnegie Hall debut.

Their backup band, incidentally, was the Orchestra of St. Luke’s, conducted by Asher Fisch, the able Israeli.

The overflow audience was filled with enthusiasm, almost culty, as befits an operatic event. For them, Ms. Netrebko and Mr. Hvorostovsky could do no wrong — even when they did wrong.

Ms. Netrebko was the first to sing, offering “Je veux vivre,” from Gounod’s “Roméo et Juliette.” Here she showed one of her persistent flaws: a lack of pliancy, or bend, in the voice. There is steel when there should be something more elastic. This aria needs melt, and Ms. Netrebko did not provide enough melt — vocally.

Of course, she is melting in other ways. As you may have heard, or noticed, she is not especially ugly.

Worst about her singing of “Je veux vivre” was that, toward the end, she became very, very mannered — killing the aria, killing Gounod’s momentum. But she concluded with a fairly good high C, and her public exploded.

Then Mr. Hvorostovsky emerged from the wings, in a rock-and-roll outfit: shiny leather pants, open shirt. To me, he looked ridiculous, but I am not a fashion critic. And I couldn’t help reflecting on the distance he has traveled during his time in the West: from an exponent of Russian liturgical music — he made an extraordinary album called “Credo” — to an operatic Elvis.

His opening piece was the “Toreador Song” from Bizet’s “Carmen,” and he and Mr. Fisch could not agree on a tempo. Before long, however, they settled on one. Mr. Hvorostovsky’s sound is often very, very contained — you long to pull it forward some. At times he seems to be singing into a pillow. And such was the case in the “Toreador Song.” The aria had more visual pizzazz than vocal.

Also, Mr. Hvorostovsky departed freely from the score, holding notes for as long as he wanted (for example). But it was that kind of night — a gala, sloppy night: “If it feels good, do it.”

At the outset of “Regnava nel silenzio,” from Donizetti’s “Lucia di Lammermoor,” Ms. Netrebko made some strikingly Callas-like sounds. According to reports, she hates the comparisons, but tough: They are just (and flattering). Unfortunately, she did not execute Callas-like trills. Indeed, she executed practically no trills at all — and this aria really can’t be sung without them. Furthermore, her diction was poor — mushy — and she was again mannered, interpretively.

Mr. Fisch let her get away with a lot — it was Anna Netrebko Night. A strong maestro in an opera house would not.

Ms. Netrebko did a little grabbing and straining in “Regnava nel silenzio,” and she opted out of some high-note alternatives — but she delivered a fine D at the end. In fact, she nailed it.

Duets? Oh, sure. The sopranobaritone duet repertory gives you fairly slim pickings, certainly as contrasted with the soprano-tenor duet repertory. To end the first half of the program, our stars sang the Nedda-Silvio duet from Leoncavallo’s “Pagliacci.” Each demonstrated a grasp of verismo style. And Ms. Netrebko (at last) showed the vocal, musical, and theatrical poise of which she is capable.

It was she who opened the second half, doing Dvofiák’s “Song to the Moon” (his hit from “Rusalka”). It was decently shaped, but not melting — other than visually, I mean. And Ms. Netrebko displayed her nagging tendency to sing sharp, often quite sharp.

Afterward, Mr. Hvorostovsky entered his bread-and-butter repertory, with the big number from Borodin’s “Prince Igor.” We heard his beauty of sound, his authority, his special regality. He provided a model of Russian cantilena. He sang with moving openheartedness. When he finished, I thought, “That’s a pro.”

In a famous Rachmaninoff song — known to us as “Oh, Do Not Sing to Me, Fair Maiden” — Ms. Netrebko was aided by her dark, alluring timbre. But she was not aided by her stagey, operatic gestures. She looked like Lillian Gish in a silent.

And we can place Ms. Netrebko in the pantheon of great singers who have sharped. I can think of three (easy) ones, right off the bat — two Swedes and a Greek American: Bjoerling, Nilsson, and Callas.

Perhaps inevitably, Ms. Netrebko and Mr. Hvorostovsky ended their printed program with the closing duet from Tchaikovsky’s “Eugene Onegin.” In a Tatiana, you may prefer a less severe, more lush soprano — a less steely, more tender one. But Ms. Netrebko got the job done, in her fashion. And Mr. Hvorostovsky’s accomplishments as Onegin are rightly hailed.

At encore time, you knew what to expect: one solo from her, one solo from him, and then a goodnight duet. Her solo was the aria from Lehár’s “Giuditta,” during which she pranced, danced, prowled — conducted the orchestra, swayed to it. Was this too much ham, even from an opera star on a gala night? Well, it sort of depends on how kosher you are, about such matters.

Mr. Hvorostovsky sang “Dark Eyes,” dashingly.

And then came the goodnight duet. I could think of two prominent soprano-baritone duets left to sing (leaving out the father-daughter ones): “Là ci darem la mano,” from Mozart’s “Don Giovanni,” and “Bess, You Is My Woman Now.” I was rooting for the latter. But they went with the former.

Did you know that Zerlina was a brazen hussy? Ms. Netrebko played her that way. And her stage antics almost obscured the fact that she was singing her Mozart rather badly: harshly, inaccurately. It was probably her worst singing of the night. Mr. Hvorostovsky, on the other hand, sang his part suavely and well.

And, in a way, this concert was beyond criticism. It was a night for love, and the two performers gave it, and the audience gave it back. Ms. Netrebko and Mr. Hvorostovsky, whatever their flaws and shortcomings, are two greats, as I have written many times, and will again. This night, however, was a somewhat strange one.