Selena Gomez covered 'Roar' by Katy Perry in concert ... but it sounded more like a whimper. Sel, what happened?!

At her Stars Dance concert in Fairfax, Va., on October 10, Gomez covered Perry's massive smash, but forgot the lyrics and left most of the vocal work to her background singers. You may notice that most of the actual singing you can hear happens when the mic is far away from Sel's mouth!

It's unclear whether Gomez was facing monitor issues or if the sound quality of the video doesn't do her justice, but it sounds a lot like she's struggling to hit any notes. (In fairness, Perry often has her own trials and tribulations with live vocals.)

We heart Sel and we know she can do better than this! Watch the performance above and let us know what you think.