Britney Spears found support from music A-listers like Miley Cyrus and Katy Perry as she finally opened her Las Vegas residency "Piece of Me" on Friday evening. But did fans detect some lip-syncing involved?

It just looked that way, explained Kurt Melien, entertainment programming at Caesars Entertainment Corp., because Britney performed against the recorded track "to help her through the more physically grueling parts of the set," according to the report by CBC News.

He also said that many of her songs also feature the electronic undertones that become almost a Britney staple which might appear lip-syncing but she sang the entire set.

Britney Spears appeared to be more appealing to the younger crowd compared to other headliners like Celine Dion, Paul Anka or Elton John. Also in attendance are Selena Gomez and Adam Lambert.

Daily Mail reported that Britney had seven costume changes and two wig changes as she performed 23 of her greatest hits which seemed to last more than the 90-minute duration of the residency at the Planet Hollywood Resort & Casino.

Britney led her audience to a nostalgic tour to her successful career as she performed "Oops ... I Did It Again" or "Baby One More Time." She also performed "Circus," "Toxic," "Lucky," and "Work Bitch" to the delight of the packed 7,000-capacity auditorium.

But this is Las Vegas after all and everything in Sin City is exaggerated so each single is accompanied by a performance backed by athletic dancers to show "enough theatrics to please those hoping for a spectacle," Daily Mail added.

At one point, Mario Lopez was pulled out of the audience for the song "Freak Show" and was dressed in leather bondage suit before Britney Spears "spanked" him, presumably for being a very bad boy.

Spears was paid $15 million for the two-year residency which will reportedly involve 100 shows. Judging by the reception during the opening show, executives are already considering of extending the show.