It's Showtime! Britney Spears Hits The Stage In Las Vegas, But Is She Singing Live? Watch The Video Of Her Sneak Peek Performance

After months of over-the-top promotions and lots of speculation about whether she could pull it off, Britney Spears finally offered up a full run-through of her Las Vegas spectacular, "Piece of Me," for friends and family Thursday night. And only RadarOnline.com has the sneak peek video of what went down!

Spears took the stage for nearly an hour and a half at the Planet Hollywood casino in the final tune-up before her residency opens to an A-list crowd on Friday night.

“I’ve got chills," the mother of two tweeted prior to the show. "Last dress rehearsal for friends and family before opening night tmw. #1DayTillShowtime."

The Grammy-winning pop star ran through much of her catalog on the 100-foot stage, with a 24-song set that included hits like "Work B*tch," "Womanizer," "Toxic," and "Oops, I Did It Again."

Spears also offered up multiple costume changes, dozens of dancers and state-of-the-art special effects.

But after much speculation, did she sing live? Watch the video and decide for yourself:

youtube=https://www.youtube.com/watch?v=-qwJlvwWPqo&w=560&h=315

As RadarOnline.com previously reported, Britney announced the two-year residency in September, when she was helicoptered into the desert in a special Good Morning America appearance.

"We wanted the environment to be that way so people could come and have a good time and stand up and feel like they're in the show with me," she said upon announcing the residency. "I love Vegas. The energy here is really, really good."

Tickets are on sale now.

Do you think Spears is singing live? If not, does her dancing make up for it? Let us know in the comments!