Miley Cyrus Rocks Out At Britney Spears’ First Las Vegas Gig (VIDEO)

Britney Spears entertained thousands of fans last night at the launch of her Las Vegas residency, Piece Of Me… but one person who seemed to be having a particularly great time was a certain Miley Cyrus.

The ‘Wrecking Ball’ star shares a manager with Spears and also collaborated with her on recent album track ‘SMS (Bangerz)’, so it was no big surprise to see her having a whale of a time in the front row of the show at Sin City’s notorious Planet Hollywood venue.

As Spears performs with her army of backing dancers, Miley can be seen rocking out in front of her, singing along to all the lyrics of her smash hit ‘Till The World Ends’.

Although critics have noted their disappointment that Britney doesn’t seem to have delivered on her promise to sing completely live, the reviews have been generally positive all-round, with the star’s no-filler setlist and sky-high production values coming in for particular applause.

Britney on stage in Vegas (Splash)

Other celebs in the audience at the launch show last night included Selena Gomez, Katy Perry, Adam Lambert and Mario Lopez – the latter of whom was even called up on-stage for part of a particularly raunchy routine to her fan-favourite song ‘Freakshow’.

Piece Of Me will run on-off for around two years, with the rumoured possibility of an extension if all goes to plan.

PHOTOS: Britney Spears kicks off Las Vegas residency

Britney Spears in Las Vegas (Splash News)