Alicia Keys, Kendrick Lamar Perform On Stage in LA: 'Set the World on Fire' Tour Features Surprise Appearance From 'Poetic Justice' Rapper [VIDEO]

On Alicia Keys' March 12 stop on her "Set the World on Fire" tour in Los Angeles, she gave fans a big surprise by bringing rapper Kendrick Lamar to the stage. A fan recorded a YouTube video (below) at the concert Tuesday night showing the Compton rapper joining Keys on stage. Lamar aka "K-Dot" was just recently voted "Hottest MC" by MTV and he is set to go on his own tour this summer with his Black Hippy crew.

At the concert in LA, Keys started singing Janet Jackson's verse from "Anytime, Anyplace." After singing the verse, Lamar jumped on stage and joined in. According to VIBE, Lamar then sang "Swimming Pools (Drank)" before finishing up on stage.

A fan tweeted at Kendrick Lamar Wednesday saying, "That moment when @aliciakeys starts singing "Anytime, Anyplace" then the beat drops and @kendricklamar hits the stage for "Poetic Justice," to which the rapper re-tweeted. Lamar's surprise appearance has fans talking and even more excited for his summer tour. Lamar just recently released the music video for his hit song "Poetic Justice" featuring Janet Jackson. On February 26 the rapper also performed "Poetic Justice" on the "Late Show with Davide Letterman."

As for Keys, she is joined on tour by 27-year-old singer Miguel, whose 2012 album Kaleidoscope Dream has been met with critical acclaim. Keys told Extra's Terri Seymour before her Los Angeles concert, "Miguel's with me on the road... I feel so grounded and feel so in my element and in my space which is rare, cause it usually takes you a good 10 shows in to kind of start to figure it out so that's a big blessing."

Keys also has her son Egypt on tour with her this time. She told Extra he is already getting used to life as a rock star. "He's officially a rock star, especially the other night when I looked at the clock. It was 12:30, he was up and I was like 'Oh no!' He's young enough to be able to enjoy this process and I'm happy I can show him different places in the world and he can meet different people and he's so social and engaged... I'm happy about all that, but that bedtime, ugh."

It looks like Keys and Lamar both have a busy summer schedule ahead. Keep checking Mstarz for the latest on both artists.