The Metropolitan Opera has done well by Mozart this season, staging “The Magic Flute,” “The Marriage of Figaro,” “Don Giovanni,” and “La Clemenza di Tito.” Of course, Mozart has done well by opera, too.

The year 2006 promises to be a Mozart explosion, as we celebrate – to death – the 250th anniversary of the composer’s birth. Consider the Met’s 2004-05 season a mini-explosion.

On Friday night, the company opened up “La Clemenza di Tito,” Mozart’s last opera. A few authorities judge it his greatest. This is very much a minority opinion, but one worth pondering. The opera concerns the emperor Titus and his magnificent “clemenza,” or “clemency.” Probably the best-known excerpt from it – aside from the overture – is the mezzo aria “Parto, parto,” sung by that pathetic character, Sesto.

Friday night’s Sesto was Anne Sofie von Otter, the excellent and versatile Swede. Her “Parto, parto” may not have been one for the ages, but it was dignified, earnest, and correct. (Incidentally, a clarinetist is virtually a co-soloist in this aria, and the Met’s – Steve Williamson – handled himself well.) Ms. von Otter sang intelligently all night long, as audiences have come to expect. And she portrayed Sesto’s psychological torment without chewing scenery.

I might note the extent to which music can alter the sound of a voice. Three months ago, Ms. von Otter sang in “Pelleas et Melisande” at the Met, and in “La Clemenza di Tito” she seemed a different singer. As Melisande she was Debussyan, and as Sesto Mozartean (what else could one want?). She should be especially applauded for her Mozart, for that is the most “exposed” singing in the world. (Come to think of it, Debussy is fairly exposed, too.)

Alongside Ms. von Otter, Melanie Diener took the role of Vitellia, that Roman prima donna from hell – a prima donna who at last reforms. Ms. Diener, a German soprano, has made a career of Mozart, having sung Fiordiligi, Donna Elvira, the Countess, and now Vitellia at the Met alone. She did not have a great beginning on Friday night, sounding pillowy and uncertain. But once she warmed up, she was persuasive. She shaped her music ably, and she was decent in passagework. Also, Ms. Diener has a remarkable lower register, almost mezzo-like. Late in the opera, she sang a low G – it wasn’t perfect, but I was impressed. On the other end, she sang a number of Bs, which were sort of grabbed at, but achieved. And she showed us Vitellia in all her aspects: the harridan, the comely schemer, the penitent.

Making her Met debut was the English mezzo Sarah Connolly, who sang Annio. Her instrument proved strong and elegant, and occasionally sumptuous, and her technique was secure. It was a treat to hear those two mezzo voices – Ms. Connolly’s and Ms. von Otter’s – entwined. We will soon have a chance to experience Ms. Connolly in recital: She takes the stage of Weill Recital Hall (upstairs at Carnegie) on May 16.

Heidi Grant Murphy was Servilia, the voice clear as water – as always – and sweeter than roses (to borrow a line from Purcell, or rather from one of his songs). And – again, characteristically – she had phenomenal control of her sound.

In the title role was Frank Lopardo, who projected imperial authority. You don’t often see that from a tenor: imperial authority (and this was a Mozart tenor, to boot). Usually our potentates are baritones and basses. Mr. Lopardo was affecting in his confusion over Sesto’s betrayal, and was, in general, every inch a Titus. In his big B-flat aria, he took many quite loud nose breaths – but, in singing, you do what you must.

Our Publio was the Italian baritone Luca Pisaroni, making his Met debut along with Sarah Connolly. He has sung this role in Salzburg, and is a budding star there. His singing is streamlined, never thick or muddy, and he has a sense of the music he is assigned. Also, he boasts some serious Italian declamation.

One may weary of praising, and describing, James Levine’s Mozart, but we soldier on. The conductor was in superb form on Friday night. Absent was any of the sluggishness or limpness that has shown up in recent years. Mr. Levine’s Mozart was alive, precise, powerful. He permits no daintiness, but he is never heavy-handed. This “Tito” was highly emotional – in its pride, fear, panic, horror, bewilderment, love – but ever Mozartean. Choruses were notably appropriate, each having its right character, and none unrestrained. Grandeur without bombast is a beautiful thing.

Let me indulge in one conductorial detail: Before the Act I duet “Ah perdona,” Mr. Levine drew from the orchestra tremendous A-major warmth. This is an unusual quality for that key.

In the pit, Kevin Murphy, at the harpsichord, led a crack continuo team.

The production is Jean-Pierre Ponnelle’s from 1984 – the only production the Met has ever had – and it serves the opera. Sets are big, marbly, and regal – like Rome. Gil Wechsler’s lighting is particularly effective, too: as when some extra light shines on Sesto, emphasizing his guilt, and aloneness. Readers may recall a review of a Salzburg “Tito” two summers ago: the multilevel garage, the little boys in underwear, the crotch-grabbing and humping. You may wish to remember such productions, when you hear people damning the “conservatism” of the Met.

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Dawn Upshaw and Richard Goode have been together for a long time, as recital partners. They have stuck with some favored repertory, too. For example, I heard them perform songs from Mussorgsky’s “Nursery” eons ago. They performed those songs at Carnegie Hall on Thursday night.

Their recital was a joint one, with both soprano and pianist featured as soloists. This makes a recital neither fish nor fowl, and I maintain there is nothing wrong with a good old vocal recital, wherein the pianist – even an established soloist – accompanies the singer. But this is the way Ms. Upshaw and Mr. Goode have chosen to do it, and they’re certainly entitled.

Speaking of sticking with repertory: Mr. Goode likes Haydn sonatas, as well he should – he plays them winningly. He began Thursday night’s affair with Haydn’s Sonata in C major, Hob. XVI:50, and it was a model of judgment. Notes passed evenly between the hands. Mr. Goode exhibited Classical taste, but he was not a pianistic mouse. Above all, he showed great respect for the musical line, and for the arc of a movement as a whole – for the arc of the entire sonata, too. The Bachian portion toward the end of the opening Allegro was exquisite.

In the Adagio, he chose a good pace – not too slow – and sang like an angel (with his right hand, I hasten to say, not with his mouth, as too many pianists do). And in the closing Allegro molto, he was fleet, mischievous, and merry. Accents were just right, and so were the rests, which are crucial. Seldom do you hear Haydn played with such character, and poise.

Then Ms. Upshaw came on, for a dozen Schumann songs: those constituting “Liederkreis,” Op. 39. We’re apt to hear several of these songs individually, but we rarely hear the complete cycle – and they make a nice feast. Ms. Upshaw is not to everyone’s taste, but (a) who is? and (b) she has legions of fans, and deserves them. Her mannerisms can annoy, but I like to say that one man’s mannerisms are another man’s endearing characteristics. I wish she would travel directly to a note instead of fishing around it – but Ms. Upshaw has traveled to the top of her profession. And the voice is marvelous, taking on an exceptional quality when it goes high: It gets “fast,” air and life racing through it.

As she sang the “Liederkreis,” Ms. Upshaw had a case of the flats, but not a debilitating case. Mainly she handled these songs with poetic authority. The voice is smallish, but it has plenty of carrying power for Carnegie Hall. The listener is not overwhelmed in his seat; he is sort of drawn in. The most famous song in Schumann’s cycle is “Mondnacht,” and Ms. Upshaw badly stretched it out. More straightforwardness would have been helpful. But “Auf einer Burg” – to cite one other song – was excellent, having a tragic dignity.

Mr. Goode was consistently fine in his accompaniments. For example, he gave us the forward movement, and restlessness, necessary in “Schone Fremde.”

After intermission, it was Debussy time, with the singer and pianist starting out with Set II of “Fetes galantes.” As Ms. Upshaw was singing the first song, “Les Ingenus,” I made a note to myself, to say something like this, in the present review: “A husk has made its way onto the voice, reminding us that Ms. Upshaw is no longer a girl, although she may look like one.” Later on in the set, she stopped – flat-out stopped singing. I thought she was suffering a memory loss. But she announced, “I have a cold” – a cold that had been enveloping her throat “for the last 45 minutes.” She asked to start again, saying, “Let me give you what I can.” She then gave what she could, which was enough.

Ms. Upshaw had a rest while Mr. Goode played two Debussy pieces that he knows well: “Ondine” and “L’Isle joyeuse.” The first was beautifully colored, shimmering, appropriately watery – delicious. The second was, of course, tasteful and correct, but not beguiling or spellbinding. This was a somewhat relaxed, too-modest reading. The final section, for example, lacked that fantastic release.

Then Ms. Upshaw returned for five songs from “The Nursery,” which she both sang and acted her way through (as is her custom). Before beginning the set, she explained that Mussorgsky wanted the singer to apply the voice of a child – and in this case, that child would be sick! The crowd laughed appreciatively, and supportively. She knows how to do a child, does Ms. Upshaw – as witness her Gretel (in Humperdinck).

There would be no encore, for the soprano had given what she could. And she and Mr. Goode will be back, fast and praiseworthy partners.