Britney Spears kicks off 'Piece of Me' tour with some seriously sexy stage styles

Britney Spears is back on tour and looking incredible!

The 36-year-old pop princess kicked off her Piece of Me tour to a sold-out crowd in Washington D.C. on Thursday night. Spears' return to the stage comes nearly seven months after the conclusion of her four-year Las Vegas residency at Planet Hollywood -- but it looked like no time had passed when she hit the stage..

While performing her fan favorites -- including "Clumsy," "Work B*tch" and "Change Your Mind (No Seas Cortes)," Spears stunned in number of sexy costumes. One stand-out stage style was an '80s-inspired workout look, while another included sparkly black-and-pink leotards with cutouts.

See photos from the show:

Spears also rocked black bedazzled bikini bottoms, fishnet tights and two different bikini tops -- one a sparkly red and another a studded black.

Fans of the singer may notice that the black style is reminiscent of the outfit Spears wore during her 2007 Video Music Awards performance of "Gimme More."

ET's Nancy O'Dell caught up with the pop star earlier this month and she revealed how she was prepping for her 30-show tour.

"This round of shows that we are doing on tour, they are back to back, so each show is like... I don't have time apart, besides flying," she said. "My show is a workout in itself. It really keeps you strong."

Spears, who revealed that her sons, 12-year-old Sean Preston and 11-year-old Jayden James, would be joining her on tour, also shared what she eats when she's on the road -- and it's not always healthy.

"Sometimes I'm just like, 'I want a hamburger!' but when I'm in work mode, I want [to eat] very clean. I want clean chicken and veggies that's it. My stomach is so sensitive, if I have a steak, I will be sick for three days," she revealed. "The burger is fine, but I have the small burgers from McDonald's. The happy meal!"

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