"It's a real carving-out process," Katy Perry says of sessions for her third LP. "I'm always fighting for 'best.'" The pop star is cagey on further details, but lets slip that she's calling from Sweden – which, not so coincidentally, is home to producer Max Martin, who helped make 2010's Teenage Dream a multiplatinum hit. Martin returned to co-write the singer's new single, "Roar," along with Perry, Dr. Luke and Bonnie McKee. "It's a more grown-up Katy," McKee recently said of the disc. "It doesn't sound like the 'California Gurls' of yesterday."