Miley Cyrus, Katy Perry, Selena Gomez and more attend.

It was a non-stop hits bonanza at the opening night of Britney Spears' "Britney: Piece of Me" show in Las Vegas on Friday night (Dec. 27).

Spears' 24-song concert was the first of a planned 100 shows over the course of the next two years at the recently revamped AXIS theater at Planet Hollywood Resort and Casino. The 90-minute show boasts a "flying" Spears, a massive rotating tree, pyrotechnics, rain, fire and an army of limber dancers.

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The all-hits revue stands in contrast to Spears' previous stage spectacles, which featured more album cuts and lesser-known new songs.

Her last tour, 2011's "Femme Fatale" trek, featured a heavy number of tunes (including non-singles) from her then-new album "Femme Fatale." However, the "Britney: Piece of Me" show was designed as a hits retrospective, and it only includes two new songs which are featured on her new album, "Britney Jean": "Work Bitch" and "Perfume."

Spears opened the show with "Work Bitch," descending from the sky in a globe-like cage. Dressed in a skin-tight, sequined bodysuit -- reminiscent of the barely-there outfit she wore in the "Toxic" music video -- she strutted around on stage, and also did some of the choreography from the "Work" video. (Yes, including that one part where she's down on the ground and doing a bicycle-pedal thing with her legs.) Spears was particularly energetic in the number, which seemed to delight the crowd. Among the celebrities in the audience: Katy Perry, Miley Cyrus, Selena Gomez, Adam Lambert and Sia.

"Womanizer" was up next -- and its bass was so loud, the sound was distorted at points. Spears was joined by her dancers again -- who were clad in head-to-toe spandex and odd masks. Think: modified SWAT team. A highlight of the performance was Spears walking on her dancers backs, a sight that drew big cheers from the audience. Clearly, they like a diva in charge.

A short "What's up Vegas!" greeting from Spears followed, along with her saying how it was "wonderful" to be here. It was only a quick hello, though, as the show then shot into her No. 1 Billboard Hot 100 hit single "3."

Spears then jumped into a triangular cage and was wheeled around by her dancers across the stage. (It immediately brought to mind how she was carted to-and-fro in cages during her 2009 "Circus" tour.) "3" was heavy on choreography borrowed from the sexy music video, thanks to a parallel bar that dropped out of the sky. It then served as the sexiest jungle gym in Vegas, as Spears and her dancers undulated their way across and around the bar.

There was an odd stuttery glitch in the audio at the end of the song, but it was difficult to tell if it was part of the show, or, if it was an actual malfunction.

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An interlude followed, and soon, Spears was back, descending from the heavens as a giant, white-winged angel, for the ballad "Everytime." After a snow shower of confetti, perhaps the "snow" that she's been mentioning to press, the song transitioned into "Baby One More Time."

Spears segued from light to dark, making a concealed costume change behind her dancers, transforming from a blond angel into a brunette vixen for "Baby." Her army of dancers kicked their way through the number with her, clad in ninja-like ensembles. After a shower of pyrotechnics, the track morphed into "Oops!…I Did It Again." The latter song got a longer treatment from Spears, compared to the shortened "Baby."

A tepid video-driven interlude was up next, where a series of TV monitors were projected on the walls of the theater, taking us through Spears' many hit music videos. Meanwhile, the stage itself was completely dark and static.

Next was "Me Against the Music," which had notably new live instrumentation from Spears' four-piece band. Spears, in a studded bustier and black leggings, recreated the "Me Against the Music" video, complete with the rickety wooden-slat walls. Madonna, who was originally featured on this song, had her vocals cut out of the tune, and her verse was replaced in favor of a dance break.

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.

Spears had a moment of Vegas redemption in her next number: "Gimme More." Years after she infamously first performed the song at the Vegas-based 2007 MTV Video Music Awards, she was back for... "More." While the VMA performance was generally considered a disaster -- with Spears' sleepwalker-like dance moves and deer-caught-in-headlights reactions -- her 2013 rendition was comparably a big win. It was a short revisit to the "Gimme More" past, as the song shuffled into a brief bit of "Break the Ice," followed by "Piece of Me." For the latter cut, Spears' dancers boot-scooted around on stage in cowboy-and-cowgirl inspired plaid and denim outfits.

Up next was an interlude set to "Scream & Shout," with new performance video shot by Spears' co-star on the song, will.i.am. The song served mostly as a showcase for her dancers, who were cavorting in day-glo human-sized hamster wheels. Spears herself doesn't appear on stage for "Scream" until the tail end of the song, when it blends into her hit "Boys."

Spears told the crowd she wanted to slow things down, and she was going to do a song off her new album, "Britney Jean": "Perfume." The staging of this particular number could not have been more simple: Spears sat on a stool and… that's it. It would seem that this is a performance that could easily be switched out for something else at a later date. In her recent E! documentary about the "Piece of Me" show, Spears and her production team indicated that the show's setlist could change over time.

Miley Cyrus became a surprise part of the show during the "Get Naked" interlude, when a couple of Spears' dancers slinked their way down the catwalk towards the audience. One of the female dancers got in close to Cyrus, who was standing directly in front of the stage. Cyrus was game, and, with drink in hand, playfully stroked the dancer's face. Everyone in the audience that could see Cyrus quickly lost their marbles, probably wondering if Cyrus was going to crawl on stage and join the show; unfortunately, she didn't.

Spears soon emerged on a throne-like contraption -- equipped with water features and fountains -- for "I'm A Slave 4 U." It was an aqua orgy of dancers in masks and tiny, tight shorts, while wet hair whipped back and forth. Spears laughed to the audience after the song, telling them "I got so wet!"

It was "time to find a hottie" (Spears' words) in "Freakshow," as her female dancers plucked an unsuspecting male audience member from the crowd to drag on stage. Of course, since it was opening night, this was no ordinary audience member -- instead, it was TV host Mario Lopez. He was a good sport, and went along with Spears' dancers, who outfitted him in a harness and made him crawl around. Spears herself amusingly whipped Lopez -- but it was all in cheeky fun.

A very loud "Do Somethin'" (with chair choreography) came next, before an elaborate tribute to "Circus" was unveiled. Spears appeared from the back of the stage, in the center of a fiery ring, very much a circus showgirl. A cool rendition of "I Wanna Go" followed, where Spears dances with six mirror images of herself. The mirrors, that are moved around by her dancers, are screens showing pre-recorded performances.

After a stark performance of a reworked version of "Lucky," it was time for the big finale, led by a high-flying version of "Toxic." A huge rotating tree materialized from the back of the stage, with Spears atop one of its upper branches. The song reached its peak when Spears flew into the air suspended by wires, and descended down to the stage to join her dancers. It led to remixes of both "Stronger" and "Crazy," the latter of which was positively thumpy. Spears' live vocals were again seemingly audible in "Crazy," as she sung over a recorded track.

It was time for Spears to "give it up" for the dancers and the band, though none of them got name-checked personally.

But, Spears then asked the crowd: "Do you guys want one more song? I can't hear you!" She didn't wait more than a second before jumping into the final tune of the night, the rain-soaked "Till the World Ends." It ended dramatically with Spears ascending into the back of the stage -- again in her globe-cage -- as her dancers frolicked in the downpour.

Spears' "Piece of Me" show next plays Planet Hollywood on Dec. 28, followed by shows on Dec. 30 and Dec. 31. It then takes a break until Jan. 29.

Check out the set list for "Britney: Piece of Me" below:

"Work Bitch"

"Womanizer"

"3"

"Everytime"

"…Baby One More Time"

"Oops!…I Did It Again!"

"Me Against the Music"

"Gimme More"

"Break the Ice"

"Piece of Me"

"Scream & Shout"

"Boys"

"Perfume"

"Get Naked (I Got a Plan)"

"I'm a Slave 4 U"

"Freakshow"

"Do Somethin'"

"Circus"

"I Wanna Go"

"Lucky"

"Toxic"

"Stronger"

"Crazy"

Encore / "Till the World Ends"