A few weeks ago, Skrillex and Diplo headlined the annual Hard Summer Music Festival in southern California. The two prolific producers had a surprise for fans as they brought out Justin Bieber to perform their track 'Where Are Ü Now.' Exclusive footage from the performance and backstage can be enjoyed above. Look for Justin Bieber to deliver new music at the end of the month, and for more information on the release of his next album click here. 'Where Are Ü Now' can be purchased on iTunes.