The 26-year-old singer burst into tears whilst performing her latest single Firework at the Radio 1 Teen Awards over the weekend and said stage-fright was to blame.
She told the Daily Star, 'I was emotional before I sang Firework.
'I got chills and butterflies - it's a huge adrenaline rush. All the hairs stick up on my body and sometimes I don't even have to sing because the crowds sing it louder.
'I still feel nervous performing to crowds. It's not that I don't feel ready but I worry that they'll rush the stage as they're all screaming my name or I feel like a wanna yack.'