If you’re one of thousands attending Justin Bieber’s stadium-sized Purpose tour this month in Europe, you’re in for an added musical treat: Bieber has enlisted The Knocks as his supporting act. The electronic DJ duo of James “JPatt” Patterson and Ben “B-Roc” Ruttner are known for their funk and R&B-inflected electropop (you’ve probably heard last year’s “Classic”). Their newest single, “HEAT” featuring the vocals of the X Ambassadors’s Sam Nelson Harris, is a syrupy, repeat-worthy track with echoes of the looping melodies and dolphin-like calls Bieber and his collaborators have worked into hits like “Where R Ü Now.” “I’m so tired of getting wasted every night / I’m tired of sleeping next to your replacement every night,” Harris sings in his signature smooth tones.