True to her words, Stefani is a woman defined by incongruities: on stage, she's a rock 'em sock 'em fount of sweat and adrenaline, swinging her fists at nothing in particular, pistoning her knees high up in the air, her muscles twitching as if an electrical current was being passed though them.

But the alpha female who grabbed the near-capacity crowd by the lapels on Saturday night at the Mandalay Bay Events Center seemed like a wholly different beast than the bundle of insecurities whom she gives voice to in her band's songs, fretting about motherhood and failed relationships, almost always placing any blame squarely upon her sinewy shoulders.

This has long been Stefani's bread and butter: projecting strength while singing of vulnerability.

And so as No Doubt kicked off their first tour in five years with an invigorated 18-song set as the headliners of the 12th annual Tiger Jam benefit concert, there was a twinge of uncertainty in the air.

"We're doing this tour because we want to be inspired," Stefani announced early on, alluding to the difficulties the band has had in writing a new album. "It's up to you guys if we make another record."

Well, if that's the case, might as well book the studio time now.

Egged on by loud, lusty approval throughout the show, No Doubt certainly didn't seem like a band that had just spent half a decade on the shelf.

They seemed eager to make up for lost time, dancing around in circles, spinning themselves dizzy, bounding across the stage like they were at a track meet.

The band fired off three fan favorites right from the get go (bouncy show opener "Spiderwebs," the cocksure strut of "Hella Good," the languid limbo of "Underneath It All"), eventually balancing those radio staples with deeper album cuts from their breakout 1995 disc "Tragic Kingdom" ("Are You Happy?" "Different People," the first No Doubt song Stefani ever wrote lyrics for).

They also aired a trio of covers (The Skatalites' largely instrumental "Guns of Navarone," Tall Talk's "It's My Life," Adam and the Ants' percussive "Stand and Deliver").

The band tinkered with their tunes here and there, taking their feet off the accelerator during "Excuse Me Mister," turning the up-tempo kiss off into a ruminative, downbeat waltz. During tropical hit "Hey Baby," guitarist Tom DuMont strapped on a Keytar and added still more laser fire synth zaps to the feel-good festivities.

Through it all, the band remained in a jubilant mood, big smiles plastered across their faces, even when a crowd member was caught napping close to the stage.

"This is the first show where someone is actually sleeping in the front row," Stefani observed. "This is a milestone for us."

Tongue removed from cheek, this did seem like a significant night for the band, as they tried -- successfully -- to recapture their mojo, culminating with Stefani bounding to the back of the arena to be engulfed by an adoring crowd during "Just A Girl," before a three-song encore.

"Sometimes it's hard to keep on running," she had sung earlier. "We work so much to keep it going."

And at least for one evening, those labors weren't in vain.

Contact Jason Bracelin at 383-0476 or e-mail him at jbracelin@reviewjournal.com.