Mary J Blige at the 2012 iHeartRadio Music Festival

"Giving fans more than they expected, Mary J Blige brought out Prince to join her on state at the 2012 iHeartRadio Music Festival on Saturday (September 22).

After the R&B powerhouse belted out hits like "Fine," she stopped her band to announce, "I got a real good friend in the building. He's one of the most amazing artists to ever walk the earth."

(SOURCE: http://celebrity-gossip.net/iheartradio-music-festival-2012/mary-j-blige-surprises-fans-prince-duet-iheartradio-fest-731336"