Selena Gomez was looking adorably retro-cool with her new blonde, cropped 'do, dark roots showing for effect, at the American Music Awards Sunday night. The singer posted pix of her new look just ahead of the show, going for a throwback-y kind of vibe in the mostly black-and-white pix.

But all the cuteness came to a screeching halt when Selena took to the stage last night -- for the first time all year -- the first time since her kidney transplant this summer -- and haters and fans alike took to social media to criticize Gomez for apparently lip-syncing her new single "Wolves." Some say she wasn't lip-syncing at all, but singing against a backing track, which isn't uncommon at awards shows and certainly not for concerts, while others defend SG claiming she was 100% singing live. Watch below ... what do YOU think?