Although “Tosca” is set specifically in 19th-century Rome, it felt more like the second century at the Metropolitan Opera on Saturday night, when soprano Deborah Voigt was thrown to the lions for her New York debut in the role. Until recently the darling of fans and critics, Ms.Voigt has rapidly fallen from grace with some mystifyingly equivocal performances. Thus it was hard not to get caught up in the drama of whether she would receive the thumbs up or down from this notoriously fickle crowd.

I’m sorry to be the bearer of bad news, but Ms. Voigt gave a relatively weak performance. Although reports of her demise have been slightly exaggerated, she seems to have lost a good deal of her confidence. When she debuted as Elisabeth last season in the Met’s “Tannhauser,” her entrance was incandescent – so much so, in fact, that she had trouble sustaining that level of artistry for the remainder of the show.This evening, as Floria Tosca, she commenced tentatively and took quite a bit of time before intoning at full volume.

Ms.Voigt did a relatively good job of staying on pitch, but a rather wobbly top line plagued her all evening. She never seemed to be in the zone, and delivered occasional notes almost at a holler. Certainly there were people pulling for her: After a rather tepid “Vissi d’arte,” one patron emitted a rather crackly cry of “brava,” followed by a decent ovation. But I found this big number strangely unmoving.

For “Tosca,” there must also be a fine sense of acting, if only as a gesture of respect to the Sarah Bernhardt original. Ms. Voigt was not comfortable in this arena, either, seeming rather stiff and nervous throughout. Perhaps this was the fault of director Sharon Thomas, but on the occasion of that most dramatic line in all of Italian opera – “This is Tosca’s kiss!” – the soprano had her back to the audience and the words were lost somewhere in the flies. As a whole, this performance was lukewarm at best and certainly not what this superstar wannabe needed at this critical juncture.

As for the rest, the Zeffirelli production may be a little dusty, but it is magically evocative of Rome. Met perennial Franco Farina filled in admirably for the ailing Marcello Giordani, keeping his tendency to bellow in check most of the time. But he has the bad habit of exaggeratedly separating all his notes; if he were an instrumentalist, I would say he did not possess a singing line.

I loved the rather over-the-top Sacristan of Paul Plishka and was impressed with the richness of voice of bass Richard Vernon as Sciarrone.And Carlo Rizzi’s conducting was unabashedly dramatic.

But the performance of the evening belonged to James Morris. Here was a Scarpia not just evil and imposing but also disturbingly human. Strong and secure in the lower register, Mr. Morris weaved a rich legato on top that stood out by contrast to his two co-stars.This created an odd, Mephistophelean moral universe in which the villain was the far superior singer. Judging by the snippets of conversation heard in the lobby, the highlight of this evening was his soliloquy “Va, Tosca! Nel tuo cuor s’annida Scarpia,” accompanied by the superb Met chorus chanting the Te Deum. This was an incredibly powerful scene.

Ms. Voigt may need to take a year off and rethink her repertoire. She has prudently withdrawn her name for consideration as the Met’s new Brunnhilde, and rightly so. She has simply hit a rough patch. There is no reason to assume that leap from the parapet is a portent of her future career path.

***

Gustav Mahler was haunted by the myth that reigned in his day that great composers die after completing their ninth symphonies. Beethoven, Schubert and Bruckner all expired under these circumstances (Bruckner only completed the first three movements), and Dvorak also completed nine symphonies before his death. Thus when Mahler completed the next symphony after his eighth, he declined to label it No. 9, choosing instead to capitalize on its song-filled structure to call it “Das Lied von der Erde” (“The Song of the Earth”).

Buffeted by a series of cruel shocks in his personal life, Mahler retreated into a volume of poetry accumulated by Hans Bethge and titled “The Chinese Flute.” The anthology was very popular in Vienna, and featured the poetry of the ancient Li-Tai-Po. (Anton Webern also set Li’s poetry to music, and the Swedish composer Sigurd von Koch’s song cycle “The Wild Swans” of 1918 is based on the same Bethge volume.) These verses, with their premonitions of death, were ideally suited to Mahler’s thanatological song cycle.

“Das Lied” was featured on Friday evening as the Philadelphia Orchestra continued its own Mahler cycle at Carnegie Hall. Christoph Eschenbach had at his disposal two of the top American singers of our day, tenor Paul Groves and baritone Thomas Hampson. This should have been a great performance, but it was not.

Mr. Groves has a large heldentenor voice, but even he could hardly be heard over the blaring accompaniment of “The Drinking Song of Earth’s Misery.” There was little sense that the instrumental ensemble was attempting to merge with the soloists; instead, they went their own way at an off-the-charts decibel level. (Interestingly, this highly skilled assemblage can actually sustain triple forte without any apparent loss of intonation.) Mr. Groves deserves praise for resisting the temptation of degenerating into shouting. “Of Youth” was better balanced, but the Mahlerian requirements of Oriental delicacy were met only with ponderousness from Mr. Eschenbach.

Mr. Hampson had a simply awful night. Clearly indisposed, he sat on extra cushions and drank a lot of water as he soldiered on. In “The Lonely One in Autumn,” he could not hit any of his high tones, and by the time he reached “Of Beauty” he couldn’t buy a note in tune. He tried sucking in instead of breathing out and even attempted a crackly falsetto, but nothing worked. The show must go on and all that, but he and the audience would have been better served had he decided to sit this one out.

I enjoyed the performance of Beethoven’s Symphony No. 8, on the other hand. I will describe the phrasing as elastic, even though a case could easily be made for labeling it willful. Certainly there was little sense of fealty to the score: Mr. Eschenbach stretched and shaped snippets of melodic line as if he were at a taffy pull.

I would have wished for a far less polite version, but the sound of the ensemble was thrilling. Those of us who have suffered through so many desiccated versions of the music of the Classical era in recent years appreciate the zaftig intonations of a fully fleshed-out orchestra.Last season the group was reseated into the antiphonal platform position and the freshness of the second violins sitting at the conductor’s immediate right produced some interesting moments of clarity, in particular the pizzicatos of the Allegretto scherzando. Say what you will about Maestro Eschenbach, but at least he is not afraid to fiddle with the previously sacrosanct “fabulous Philadelphian” sound.

“Tosca” will be performed again on April 26 & 29, and May 5, 8, 11 & 16 at the Metropolitan Opera House (Lincoln Center, 212-362-6000).