at most concerts backtracking is used, which is an instrumental with the chorus being on it. This is what was used here, just like anywhere else, and not just because it was Rihanna singing, but the same thing is used for most performers. She was singing along with it but since there was a backtracking she wasn't as loud. It's funny how u keep posting things about Rihanna just to continue to hate. Don't be jealous because she's very beautiful and you only wish to be her. AND she's not the first person to lip-sync anyway. Get it Together, Bitch!