An unexpected guest dropped in on Alicia Keys's Los Angeles show Tuesday night.  A fan captured video of Alicia singing the first few lines of Janet Jackson's "Anytime, Anyplace."  Then, as her voice trails off, Kendrick Lamar's "Poetic Justice" kicks in.  "Kendrick! Come on the stage with me," Alicia shouts to the Compton rapper, who appears dressed in all white for the show in his hometown.

The crowd went wild, of course, as Kendrick delivered his verses from the good kid, m.A.A.d city single.  After the show, he re-tweeted a message from one concert-goer who was still in awe over "That moment when @aliciakeys starts singing "Anytime, Anyplace" then the beat drops and @kendricklamar hits the stage for "Poetic Justice."

Before the show, Alicia also released a special music video featuring photos uploaded by her Los Angeles fans.  The visual is part of a special project that Alicia is doing in her role as Blackberry's Global Creative Director.  She's been asking fans in each city on her Set the World on Fire tour to share personal photos for a custom video that's projected on stage during her shows.

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