Music Britney Spears Set To Perform at Billboard Music Awards By Len Brown 10:31 AM PDT, May 21, 2011 Getty Images Britney Spears is set to take the stage not once, but twice, at Sunday's 2011 Billboard Music Awards in Las Vegas, according to US. The pop princess will perform Rihanna's hit "S&M," alongside the R&B singer, possibly as the opening act. Britney will then follow it up to perform the remix of her song "Till The World Ends" with Nicki Minaj, making it the first time the two divas hit the stage together before their tour this summer. "People will definitely be talking about it the next day," a source said regarding Britney's return to live TV. "It's gonna be big."