Britney Spears [1] might have dated a member of *NSYNC [2], but on Sunday she got up close and personal with one of the Backstreet Boys. During her Las Vegas Piece of Me concert, the 35-year-old superstar invited Howie Dorough on stage for a provocative performance of "Freakshow," and things got steamy. Howie, fresh off of his performance at the ACM Awards [3], happily crawled around on all fours while Britney whipped him. "Thank you so much for coming out here and dancing with us," Britney said before signing a t-shirt for him. "Thank you. Bye, baby. Everyone give it up for Howie!"

The Backstreet Boys are currently headlining their own Vegas residency [4], which makes it easy for them to pop by Britney's show. In February, A.J. McLean hung out with her backstage [5] and had nothing but good things to say [6] about her performance. "Her body's back! She looks fantastic! Britney's back, man," he said. "She's doing fantastic, dude. She was on her A game. She looked good, she sounded good, [and] she was killing it dancing."