Beyoncé’s “XO” gets folkified as he covers the track during a show in Adelaide, Australia, on Tuesday (April 15). The Grammy winning artist played the guitar and harmonica as he stripped Bey’s songs to an acoustic melody. Mayer also took to his Twitter to give Yonce some musical praise, ““The best thing about Beyoncé? The breakin her voice on the first ‘baby, love me lights out’ in XO. Real and raw,” he said. Press play.