According to a Yahoo! Music report, "Britney's ex-X Factor' co-star, Mario Lopez, even got in on the action, when Britney looked for a "hottie" in the crowd, then dragged Mario up onstage for a mildly titillating S&M-themed vignette, during which she wrapped the former A.C. Slater in chains and swatted him with a riding crop. (Important side note: This was as sexy as the 32-year-old mother-of-two ever got on stage.)"
A YouTube video of the performance shows that Spears' backup dancers actually interacted more with Lopez than Spears did. At one point, they had Lopez crawling on all fours, like a submissive plaything. At the end of the faux S&M act, Spears gave Lopez a Britney Spears T-shirt.
Other celebrities who were in the audience at the show included Miley Cyrus, Selena Gomez, Katy Perry, Adam Lambert, Holly Madison, Jamie Lynn Spears, Sia and Pauly D, the former "former "Jersey Shore" star who used to work as a DJ on Spears' "Femme Fatale" tour.
Reviews of Spears' opening night at Planet Hollywood in Las Vegas noted that Spears lip synced through most if not almost all of her "Piece of Me" show. Not surprisingly, most of the reviews from music critics were mixed-to-negative. In addition to getting slammed for not singing live, Spears also got a lot of criticism for her lackluster dancing.
But some fans didn't seem to care that they paid to see Spears lip syncing. As the Associated Press noted: "The young-for-Vegas crowd was there for the spectacle, which included acrobatics, a ring of fire, confetti, and a frequently airborne Spears."
Spears was a judge on "The X Factor" U.S. in 2012, the same year that Lopez joined the show. Spears got mostly negative reviews during her one-season stint as an "X Factor" judge, with many critics saying that she was a "dull" and "robotic" judge. She was reportedly paid $15 million to be a judge on "The X Factor," and it's reportedly the same amount she's getting paid for her Las Vegas residency, which runs through 2015.
Lopez, who also hosts the celebrity news show "Extra," became famous in the late 1980s for his co-starring role as high-school jock A.C. Slater in the TV series "Saved by the Bell."
Here's a sampling of reviews of Spears' opening night for her "Britney: Piece of Me" Las Vegas residency:
"The young-for-Vegas crowd was there for the danceable hits and the spectacle, which included acrobatics, a ring of fire, confetti, a live band, frenetic costume changes and a frequently airborne Spears. The show's production values are unusually high for a casino residency, calling to mind the golden age of music videos. Its high-concept set pieces featured a cadre of backup dancers who danced in human-sized hamster wheels and somersaulted over the Grammy-winning star."
"Notably, 'Me Against the Music' was one of the few songs during the show where hints of Spears' live vocals were audible. (Though, she was still singing over the original studio vocals of 'Me Against the Music.') The vast majority of the show was lip-synced, and only occasionally were any seemingly live vocals heard. There was a certain thrill in actually hearing Spears breathing into the microphone -- however infrequent."
"While it’s fun, the show is far from perfect. The video interstitial showing her videos from the past two decades is a missed opportunity to show us some behind-the-scenes footage or a personal story from Britney herself. Beyond showing her various eras, the show doesn’t have an overarching theme that sticks with you, and while the tricks are cool to see, they seem a little slapped together and don’t flow smoothly. And then there’s the is-she-or-isn’t-she lip syncing. But we’re not here to see Maria Callas. We’re here to see a pop star put on a choreographed, rehearsed-down-to-the-second stage show, and the best part is the dancing. Like Madonna before her, Britney is smart to make stars out of her dancers, and they nearly steal the show in parts."
"After literally years of anticipation, Britney Spears finally debuted her resident show Piece of Me at Planet Hollywood’s newly christened Axis theater on Friday night and the result was … exactly as expected. That’s not necessarily a bad thing — Spears’ worst moments come when she’s unpredictable, and she’s never been a daringly original artist. As a singer, she mostly functions as a cog in the Britney Spears machine, serving as the face for a brand that’s maintained by dozens of equally (if not more) important people behind the scenes."
"True to her word, Britney Spears poured on the cheese during opening night of her 'Piece of Me' Las Vegas residency at Planet Hollywood, where she raced through a whopping 23 hit singles in just 90 minutes ... Spears delivered on her signature style of larger-than-life production, blaring beats and rapid-fire dance moves, whirling through seven costume changes and even a couple of wig changes ... That's not to say her vocals weren't live. At times, her sweet voice shone through the backing, or we could hear her catching her breath between numbers. Other times, we'd watch her run up a set of stairs while her voice didn't miss a beat."
"No surprise then that at 32, with more than two decades of performing under her belt, Ms. Spears has already arrived at the laurel-resting portion of her career, landing in a greatest-hits production so winning that it barely needs her at all. Mostly, she’s a pinball during the 90-minute extravaganza 'Britney: Piece of Me,' her new residency at the Axis Theater at Planet Hollywood Resort & Casino here that had its debut on Friday. Magical things are happening all around her — ornate sets, clever video displays, fiery dancing — but Ms. Spears is there mostly to activate memories, to be a souvenir for the eyes. Rarely did the voice booming out over the speakers appear to be coming directly from Ms. Spears’s mouth. Always a notch or three less committed than her backup dancers, she was at times downright listless."
"Viewed through a lens of diminished expectations (Britney's bar for success was reset in 2007 after her well-publicized breakdown), 'Britney: Piece of Me' is an entertaining tour through the 32-year-old star's nearly 15-year recording career. Compared to pop spectacles staged by Madonna and Beyoncé (and even Katy Perry, who was in attendance for Spears' opening night along with Miley Cyrus), however, the weaknesses that remain in Spears' live act are stark. While the show's producers claim Spears is singing along with backing tracks of her own voice, there was little evidence Britney sang a note live. Her banter with the audience ranged from canned ('What's up, Vegas? I can't hear you!') to baffling in light of her very public struggles with substance abuse ('I feel high!' she proclaimed before the final song). Her dancing, touted as the show's linchpin, was often lackadaisical and – as has become the norm for Spears – reliant on arm movements."
"Eye candy was everywhere, whether in the form of the taut dancers' bodies or the lavish sets, none more so than the Circus-themed number featuring creepy human marionettes and raging flames, with Spears delivered on stage in the middle of a ring of fire. When she sang, 'All eyes on me in the center of the ring,' it was redundant. If a criticism must be meted out, it would center on Spears' insistence that the well-oiled show not deviate remotely from its tracks. What little she did engage with the crowd ('How are you doin', Las Vegas?') stuck to the same script as Thursday's preview show before casino industry workers. One longed for a bit more intimacy from Spears, especially on opening night with stars on hand. But if the singer has been consistent on one point over the years it's that she's actually by nature shy."
"As Britney Spears kicked off her much-hyped "Piece of Me" residency at Las Vegas's Planet Hollywood resort, descending from the vaulted ceiling in a futuristic gilded cage while wearing what appeared to be her rhinestoned nude bodysuit from the 2000 VMAs, the burning question inside the 4,600-seat theater was: Was she singing live? The answer: Eh, probably not. Not most of the time, anyway. The relatively intimate setting made that pretty obvious. But then, there was another, almost equally valid question: Did it even matter? And once again, the answer was, well, no. Not really."