The second annual iHeartRadio Music Festival was nothing short of star-studded. Headliners for the two-day fest at Las Vegas' MGM Grand included mainstream radio hitsmakers like Rihanna, Taylor Swift, No Doubt, Green Day, Pink, Pitbull, Lil Wayne and more. On Day Two of the festival Mary J. Blige brought out a very special unannounced guest: Prince. Decked out in a psychedellic ensemble that would make Jimi Hendrix proud, the Purple One joined Blige for "Sweet Thing" and his own jam, "Nothing Compares 2 U," complete with a guitar jam.
After her set, the 41-year-old R&B star tweeted the news to her fans. "Just brought out Prince to share my special moment at the #iHeartRadio Music Festival." Watch the performance below.