Britney Spears's white terry-cloth robe dropped to the floor, revealing a sequin-covered body stocking. She stepped into a bathtub that, like her bodysuit, was see-through. In shadow to her left, like silhouettes seen through hotel room windows, men and women in beds mimed passionate sex with one another.

Beneath them a man wearing only tight white briefs splayed his legs and gyrated on a bed. After her mock bath Ms. Spears, wearing a pink bra and panties, rolled around in bed with him as two male dancers to their left took off each other's pants and danced suggestively together.

So went just a few minutes of the Onyx Hotel Tour, Ms. Spears's first roadshow in nearly two years, which opened on Tuesday night at the San Diego Sports Arena. And for a woman who has said that she's sick of being in the headlines, it's certainly designed to grab more. With a suggestive, racy show that contains very little actual singing, she seems to have outdone even her mentor, Madonna.

If the visuals in the 15-song, 7-costume performance won't get Ms. Spears more attention, then the words spoken onstage will. Addressing the "cute boys" in the sold-out crowd, she gamely mocked herself, telling them: "Who knows? Maybe if you're really lucky, I might marry you."

Before sitting down to pretend to play the piano for the next song, Ms. Spears turned more serious. "The last six months have been like a roller coaster, with a lot of ups and a lot of downs," she said. "But I think that's made me who I am."

"We all know how to laugh, how to cry, how to be held tight, and we all know heartbreak," she continued before singing "Everytime," her ballad about breaking up with Justin Timberlake. It was the only song that she appeared to sing unaccompanied by backing tapes. At least she crooned the beginning of the song that way before the recorded support kicked in.

When Kelis, the singer who was Ms. Spears's opening act, sang her hit "Milkshake," she was audibly winded after just a few dance moves. Ms. Spears executed even more calisthenic routines throughout most of her numbers, and rarely could the slightest puff or pant be heard in the vocals. Further evidence that the microphone was not on came when she brushed loose strands of hair off the mouthpiece, and the sound of the motion could not be heard in the arena.

The lip-synching was neither a surprise nor a concern, however, because Ms. Spears is a star built not for singing but for entertaining. Her show was more a theater-and-dance spectacle than an actual concert, with the staging equal parts Cirque de Soleil and the redeveloped Times Square. Fans stumbled out of the show dazed from the onslaught of blinking light banks, flash pots, confetti canons, dance numbers and videos. At times the show seemed more like a Las Vegas tribute to Ms. Spears than a concert by Ms. Spears herself.

Like Christina Aguilera, Ms. Spears seems to feel that she has outgrown her early hits and image. So she performed nearly every song from her latest CD, "In the Zone" (Jive), relegating teen-pop hits like ". . . Baby One More Time," "(You Drive Me) Crazy" and "Oops! . . . I Did It Again" to a medley that converted them into slow, jazzy cabaret numbers.

The theme of the show was a hotel on the edge of reality that Ms. Spears checks into, a magical wonderland of the subconscious where, according to a creepy character who plays the M.C., your "darkest side" can be explored, with "titillation" guaranteed. The Onyx Hotel Tour, a three-month international trek that comes to East Rutherford, N.J., on April 10, was a great spectacle, but it was also one of the weakest concept shows since U2's PopMart tour. The staging highlight was "Shadow," in which Ms. Spears was raised over the stage in a swing, sitting at the crest of an immense, M-shaped blue ribbon, with performers twirling in the fabric. With her dance-driven Top 40 pop sounding out of date, at least she's already prepared for tenure in the casinos.