Like last year's album,

I Am . . . Sasha Fierce

, Beyoncé Knowles' current tour is devoted to the idea of dual personalities. There's sweet, vulnerable Beyoncé, and then there's her take-no-prisoners alter ego Sasha, who sports a titanium "roboglove" on one hand to signify her strength and machine-like precision. Even the musicians in her all-female band, Suga Mama, come in multiples: two keyboard players, two drummers, three apiece of horns and backing singers.

The only trouble with Sasha Fierce's duality is that two sides are hardly enough to contain all of Beyoncé's personae, which may be why the title of her I Am . . . tour leaves the sentence provocatively unfinished.

At the Wachovia Center on Friday night, she shuffled through costume changes and musical styles so quickly, you could have gotten whiplash keeping track. There was a sparkly gold bustier with a bow at the back; an all-white ensemble that morphed into a wedding dress; and a super-heroic get-up, complete with silver cape, whose chunky light-up ornaments raised the possibility that she might at any moment transform into a motorcycle and drive off the stage.

In fact, the whole show was a vehicle, a sleek contraption designed to demonstrate her considerable skills as singer, dancer, and bandleader, not to mention clothes horse. For "Freakum Dress" and "Get Me Bodied," she was a temptress, her body swiveling, and her voice leaping from high notes to low.

"Broken-Hearted Girl" and "Scared of Lonely" showed off a more vulnerable side, or at least a simulacrum of one, as well as her dazzling way with a ballad. Although she occasionally ceded choruses to her backing singers or a programmed track, she managed to hold onto enough breath to belt out songs while performing routines that would make an aerobics instructor pant.

As if her own songs weren't enough, she drew bits and pieces from other singers' catalogues, lingering just long enough to make her point. A James Brown horn riff was testament to her skills as a bandleader (or at least her discerning choice in musical directors), and a segue from her own "If I Were a Boy" into Alanis Morrisette's "You Oughta Know" proved that she could rock as well as swing.

Her version of Michael Jackson's "I Can't Help It" served a different purpose, paying tribute to the man she called "my hero."

"If you know anything about me, you know the only reason I'm here is because of Michael Jackson," she told the crowd, her voice catching ever so slightly. "He taught me just about everything I know."

"I will always give you a hundred percent of me," Beyoncé said at the end of the show, standing atop a terraced riser that suggested an ancient pyramid, with the singer as both high priest and human sacrifice.

But the more lasting image was the harness she used to fly above the crowd, turning a full somersault on her way to a secondary stage. As her body spun, pieces of gold glitter detached themselves from her costume and floated down to earth, lingering briefly before getting lost in the light.