Song is the first to be taken from Lamar's new album, the follow-up to 2012's 'Good Kid, MAAD City'
Rapper included the song in a surprise set at the 'We Day Toronto' educational event
Three-day event culminates in gig on private island in the Bermuda Triangle
The rapper visited the singer's house in St Louis
The Compton rapper unveils the first track from his new studio album
New track 'i' is rumoured to be unveiled next week
Rapper has revealed the single's cover via Twitter
Eric Reed and Willie Jones III of former jazz ensemble Black Note are suing US rapper
Fourteen minute film will be revealed at Next Fest in Los Angeles on August 9
Rapper opens up about progress being made on his forthcoming third studio album
US star raps along to tracks including 'My Name Is' and 50 Cent's 'Candy Shop'
Rapper Future also appears on new song
Lamar's third album is set for release this autumn
LA rapper performs cover version at first ever iHeartMusic Awards last night (May 1)
Alicia Keys and Hans Zimmer also join the rapper on Fallon
Prosecutors claim the athlete argued with girlfriend Reeva Steenkamp over 'Bitch Don't Kill My Vibe'
US rapper's last album, 'Good Kid, M.A.A.D City', was released in 2012
Vanilla Ice also made a surprise appearance at the event
Rapper teams up with the rock band on their hit track 'Radioactive'
Rapper left awards ceremony empty handed on Sunday (January 26)