Britney Spears introduces Miley Cyrus at IHeartRadio Music Festival, day 2, Saturday, Sept. 21, 2013 in Las Vegas, NV. (Photo by Al Powers/Powers
Britney Spears introduces Miley Cyrus at IHeartRadio Music Festival, day 2, Saturday, Sept. 21, 2013 in Las Vegas, NV. (Photo by Al Powers/Powers Imagery/Invision /AP) ( Powers Imagery )