2U David Guetta feat. Justin Bieber
Take a sneak peek backstage then see the pair perform 'All Of The Lights'.
Kanye West made a surprise appearance on stage with Rihanna as part of her 'Loud' tour.
Kanye showed up at her gig in Boston on Sunday night when her US tour came to an end.
Check out Kanye, Rihanna and their mate Heidi Klum hanging out backstage, then see RiRi perform 'All Of The Lights' with her rapper mate.