'It's in my blood to perform,' Britney tells USA TODAY

Marco della Cava | USA TODAY

LAS VEGAS — The big white snake and that awards show kiss. The electric professional highs and those crushing personal lows.

All traces of that particular tabloid queen have vanished from an airless backstage room at Planet Hollywood Resort & Casino, leaving behind only a tired, sweaty yet still smiling 32-year-old working stiff named Britney Jean Spears.

"I didn't sleep last night because I'm excited," Spears tells USA TODAY, her soft Louisiana drawl peeking out as she plops down on a leather couch after another grueling rehearsal. "But today I'm dying. I feel like I'm drunk, I'm so tired, you know?"

It's not hard to imagine the stress and strain Spears is under. For the past four months, the onetime queen of teen pop has been laboring on her new stage show, Britney: Piece of Me, a two-year, 98-gig residency that kicked off Friday at the custom-tweaked, 7,000-seat Axis theater here.

Beyond the inevitable scrutiny of a pop-culture kingdom she once ruled, there's the sheer rigor of blasting through 24 largely uptempo hits with countless costume changes and wild set pieces that include her leaping off a massive fake tree.

But for Spears, whose at-home dramas — ranging from divorce to hospitalization — sometimes appeared to threaten her onstage dreams, it was never really if she was going to clamber back on the showbiz diving board, but when.

"It's in my blood to perform," says Spears, dressed in black dancer's tights and a football-type jersey bearing the number 25. Her bleached-blond hair is pinned to the top of her head; one hand fusses with her upper lip.

Most stars in this decidedly un-starlike state would simply refuse to be seen, but Spears seems as comfortable as your neighbor coming back from a jog.

"I'm a hometown girl, and my personality at home is the opposite of the performer in me," she says. "But then, when I'm home and haven't done anything for a while, I get really itchy and nervous and weird-feeling. Performing is my therapy, to become different people onstage."

She pauses, her voice but a whisper. "It gives me confidence. I don't have that much confidence in myself. But when I'm onstage, it's my alter ego, and it kind of does adjust my personality."

Vegas offered the perfect outlet for those dueling personas.

"I'm a family girl and (like) being in one place. Traveling around the world is really strenuous for me, being in a different bed every night, flying and everything," she says, shaking her head. "I look back now, and I don't see how I did it. This (residency) just seems ideal. It's an hour from L.A., from my home, and it's perfect."

Well, almost. Comfortable onstage since her pre-teen Mouseketeer days, Spears made a name for herself in the early 2000s as a dancing force in the model of her heroine, Madonna. But the body of a teenager is forgiving, less so the one of a thirtysomething mom. Spears recently hit the spa at a neighboring Strip hotel and confesses that she never wanted to leave, a take-me-away luxury that rivals disappearing into a favorite movie (Bridesmaids) or book (Emily Giffin's Heart of the Matter).

"These intense workouts have really been excruciating," she says, sighing. "It's probably the hardest workout I've ever done, ever in my life, getting ready for this show. I look back at my other tours, and I'm doing more songs here than I've ever done. And it's just way more, the speed of the dancing throughout."

That tempo is thanks to a catalog of hits that a much older performer would envy, ranging from her teen-vixen breakout smashes, 1998's ... Baby One More Time and 2000's Oops! … I Did It Again, to the will.i.am-helmed dance grind Work Bitch off her just-released album, Britney Jean. While this eighth effort is her slowest-selling to date — just 107,000 copies in its first week — there's enough depth to the past decade and a half of chart success to fuel the show.

"Let's remember it's been almost 15 years since her first album, and that's an anniversary to celebrate, one that makes it feel right to have a retrospective show like this," says her manager Larry Rudolph, taking direct aim at a criticism that his client (he also represents Miley Cyrus) might be too young for a Vegas residency.

"Very few performers have 15 years in the business, let alone that many years with lots of hits," he says. "Miley called me the other day and told me, 'I've just spent the past few days watching all of Britney's (music) videos, and she's unbelievable. She just murdered it every time.' This (run) is more than warranted."

While there's no debating that Spears is far younger than her Vegas residency compadres — notably Celine Dion, 45, Shania Twain, 48, and Rod Stewart, 68 — her youth is an asset when it comes to producing a high-energy, club-oriented spectacle aimed at a new and younger breed of Vegas visitor lured by the Strip's burgeoning commitment to electronic dance music. Here, Britney billboards do battle with ads for sets by all-star DJs such as Tiesto, Steve Aoki and Calvin Harris.

"My guess is this (residency) is a good bet for Vegas, as there are enough people who were teens with (Britney) and now are in their 30s and revisiting their love of her dance hits," says Gary Bongiovanni, editor of concert industry magazine Pollstar.

He adds that while any new act in town faces the challenge posed by "Vegas being, arguably, one of the busiest entertainment cities in the world," he notes that any show offering "a lot of eye candy is basically addressing what most visitors there come to expect."

But Britney could well be shooting for something far greater than simply being just another fun Vegas night out, says Rolling Stone columnist Rob Sheffield.

"With this show, she's making a bold claim on her place in pop-culture history," he says. "Everyone's always predicted a flame-out from her, but the new album shows she can expand her sound. She'll have to be bold, but this is a chance to shine."

For Spears, staying busy will be its own reward.

"I know nearly 100 shows sounds like a lot, but I'm excited," she says. "I'm the type of person who, if I don't have enough to do, I go crazy. I have to stay busy. It's a good thing to stay busy."

The plan is to do four or so shows a week, then head from a penthouse suite here back to her Los Angeles home and overseeing her boys' (Sean, 8, and Jayden, 7, with Kevin Federline) school and sports schedules, a working-mom juggling act she credits to the efficiency of a trusted assistant.

"I love my family," says Spears, whose father and conservator, Jamie, is never far from sight backstage. "I get excited being around them. For me, it's about relatives and cousins, as much as they can drive you crazy. It's about them."

If she is feeling the pressure to demonstrate that she still has what it takes professionally, she's not showing it.

"I love what I do, and at this point in my career, I don't feel like I have anything to prove," she says. "I didn't do much promotion for the new album for that reason. I don't feel like I have to do every TV show. I just want to perform and inspire people. When I'm tired and I see one of my dancers pick up my part, they inspire me. I think that's why we're here, to inspire each other."

She sips a drink from a straw. "Performing gives me a fearless feeling, like you can conquer anything. I guess it's a false confidence, actually."

In fact, certain things scare Spears.

"A lot of things do, yeah. Um, like I'm not good in social settings," she says. "And I'm not good with heights. Or any animals other than my animals. I'm scared of dogs. I have dogs, but they're tiny. I'm scared of other dogs. I got attacked by two dogs when I was younger."

Clearly, snakes are exempt from that fear, as evidenced by her memorable cultural moment, akin to Miley's MTV Video Music Awards twerk-a-thon: draping herself with a massive white python for the 2001 VMAs performance of I'm a Slave 4 U.

Spears smiles at the memory. That was a lifetime ago. A teenage dream. Her thirtysomething reality lies ahead.

"I'm happy with where I am," she says. It comes off as a statement, not a plea. And for the next two years, the world can come to Las Vegas and see for themselves.