‘Pretty Girls' Singers Britney Spears, Iggy Azalea Perform Live At Billboard Music Awards

“Pretty Girls” collaborators Britney Spears and Iggy Azalea delivered one of the most unforgettable performances at the 2015 Billboard Music Awards held at the MGM Grand Garden Arena in Las Vegas on March 17, Sunday.

The music award ceremony aired live on ABC and hosted by “Furious 7” actor Ludacris and “All Of Me” singer John Legend’s model wife Chris Teigen. It was the first time Spears and Azalea sang their collaboration song “Pretty Girls” live.

Featuring a “Star Trek” theme, Spears and Azalea performed “Pretty Girls” with a crew of dancers dressed up as silvery space aliens and neon-toned 1980s dancers. The performance was intended to promote Spears’ Las Vegas residency.

Released on May 5, “Pretty Girls” is the first song Spears and Azalea collaborated in and its music video premiered on May 13. Azalea and former One Direction member Zayn Malik’s girlfriend Perrie Edwards are among those credited as the writers of the song.

“It's not something that I ever anticipated happening," Azalea told Billboard of the collaboration song with Spears. “I loved pop music but I loved rap and I wanted to be a rapper and I didn't know I'd end up making such a crossover mesh of pop and rap where that would be a collaboration that would be possible.”

“Pretty Girls” is not the first collaboration song for both Spears and Azalea. Among Spears’ previous collaboration songs with a rapper are “Tik Tik Boom” with T.I. and “It Should Be Easy,” “Big Fat Bass” and “Scream And Shout” with will.i.am.

Azalea also has several chart-topping collaboration songs, including “Fancy” with Charli XCX “Problem” with Ariana Grande, and “Black Widow” with Rita Ora, which peaked at the Billboard Hot 100 chart at number one, two and three, respectively.

While at the red carpet for the 2015 Billboard Music Awards, Azalea Giuliana Rancic of E! News that she was feeling “very, very revamped” because of her “new change of hair and change of style,” which she said was necessary for the new album she is recording.

On the other hand, Azalea did not necessarily mention whether or not she went under the knife although she is rumored to have had a nose job and chin implant. The Australian rapper matched a baby blue crop top with skirt with sheer panels at the red carpet.