NEW YORK - The lights are on - lots and lots of them - but signs of genuine operatic habitation are intermittent in the Metropolitan Opera's production of

Thaïs

.

The 1894 Jules Massenet star vehicle was mounted for Renée Fleming - in her biggest Met season yet, she's been enshrined in the opening-night gala, the company's advertising campaign, and now in Christian Lacroix gowns created for Thaïs - and promises much to see in its noon simulcast tomorrow at movie theaters in the Philadelphia area. But maybe not more than that.

Expectations must always be adjusted for this genre of middlebrow turn-of-the-20th-century French opera, and Thaïs, which is nowhere close to the level of Massenet's Manon, doesn't give performers occasions to which they can rise but instead a series of alluring, even salacious star-turn opportunities. And if those are not fully met, you're left with a modest mid- to slow-tempo work that barely meets modern audiences halfway.

So it was at the Met on Wednesday, a dry run of sorts for tomorrow's high-def simulcast, with camera cranes levitating around in your peripheral vision, assuring a polished live experience three days hence.

But the performance failed to sell you on the illusion the piece could create on a good night. Fleming wasn't so vocally assured - hey, it happens - and conductor Jesús López-Cobos was a constant source of wonder in all the wrong ways. How could someone with such a benign, literalist temperament be tapped to lead a work that needs an interventionist to communicate what gentle content it has?

As it was, the languid sexuality of the Egyptian courtesan Thaïs had the same suave manner as her later religious conversion dramatized by the famous "Meditation" instrumental interlude for violin and orchestra.

Though the opera's climax is Thaïs' elevation to living-saint status (apparently possible in A.D. 4, when the opera is set), the music becomes a bit more excitable amid the spiritual dilemma of the fanatical Athanael, who initially converts Thaïs but after months of "prayer, fasting and flagellation" (according to the plot synopsis) arrives at her deathbed begging for sexual favors. With baritone Thomas Hampson at hand, you wondered how this intelligent singer kept a straight face, and couldn't fault him if his conviction was only 70 percent.

The one clear-cut success Wednesday was in the less-dimensional role of Nicias, Thaïs' wealthy primary client, sung by tenor Michael Schade with a far greater degree of French style and sound than you can hope for these days.

The John Cox production sensibly avoids Egyptian kitsch by resetting the story in Massenet's own time, giving the opera's Victorian-era primness and simplistic rationale (quite different from current religious conversions) a credible context. More than anything, the production compensates for the score's lack of operatic grandeur with sweeping but meaningless stairways and saturated colors - rich blues of nighttime desert skies and cherry reds appropriate to the opera's sensuality. The slightly tattered quality perhaps reflects a rough transit from the show's originator, Lyric Opera of Chicago.

Saturday could be a different story: Fleming could well summon the vocal wizardry of her excellent Thaïs recording, in which she didn't target the high notes so much as she ingeniously incorporated them into an overall veneer of supreme charm. Somebody might slip López-Cobos a double espresso (make that a triple). If nothing else, the performance could be one last chance to see a major-production Thaïs - since this one isn't likely to set off a mass Massenet conversion.

Contact music critic David Patrick Stearns at dstearns@phillynews.com.