Nice kid, that Britney Spears. She makes you want to like her. She doesn't have a great gift of song, but Lord, does she work hard to sell it.

Impossibly blond, perky and energetic, the 22-year-old onetime Disney girl hurled a nonstop 90-minute barrage of athletic dancing, splashy special effects, futuristic staging and throbbing, pounding dance drives at the capacity crowd Tuesday at the Oakland Arena.

Wheeled onstage atop a 10-foot motorized platform wearing a skin-tight black leather dominatrix number that deliciously recalled Jane Fonda in "Barbarella," Spears immediately slammed into her latest single, "Toxic." The riff-happy, bass-heavy electronica sound of her fourth album, "In the Zone," fueled the entire performance.

Surrounded by a gang of eight dancers, wearing a wireless headphone mike, she drove herself through one demanding dance number after another. With the constant costume changes that emphasized skin over cloth, Spears came off as a cross between an aerobics instructor and a Victoria's Secret model.

The huge video displays, specially produced film segments, Cirque du Soleil touches, high-tech staging and grotesque master of ceremonies (who looked like Boy George at Mardi Gras) made Spears' "Onyx Hotel Tour" pure Vegas glitz and spectacle. The star often found herself lost at the center of all this hectic activity.

In her new, purported "adult" role, Spears plays the sex bomb for all she's worth. Prancing around in pink satin lingerie and garter belt, she pretty much performed a lap dance on one of the poor guys dancing with her. But for all her adorable, coltish willingness, Spears infused the whole enterprise with more athleticism than eroticism, undermining the intended effect. Part cheerleader, part porno star, it appears the new Britney doesn't quite know what to make of herself. In her desperation to win her audience's attention, she never showed the confidence to let up for a second, to take a moment to be a real person onstage or, at least, pretend to be one.

In her brief career, Spears has made a signature style out of these razzle-dazzle, aerobic workout performances. When she stops the dance machine to get serious, things go south quickly. "We all know how to laugh," she said, flashing that million-dollar, ice princess smile and sitting at a leaf-covered piano as if she actually played the instrument. "We all know how to cry. We all know heartbreak. The road ahead keeps moving and everything makes us realize how beautiful life is."

Spears made light of her big teen pop smashes -- "... Baby One More Time" and "Oops!... Did It Again" -- performing pseudo-jazz versions of her biggest hits in a mock lounge segment. She has abandoned such frothy pop for a surprisingly hook-free pulsing techno grind, an all-purpose industrial dance- pop that suggests a new sophistication without actually achieving it.

She probably didn't even sing live. The highly polished, processed and produced vocals were awfully smooth and clear to have been actually sung by someone who was huffing and puffing so hard just talking to the audience between numbers.

But who cares? Britney Spears is not about singing. She is circus.

Only her soundman knows for sure.