NEW VIDEO 1D fans go wild after Zayn Malik and Liam Payne rip open Harry Styles' shirt on stage
One Direction were in the middle of their No 1 hit What Makes You Beautiful when Zayn, 19, and Liam, 18, stood behind Harry and ripped open his white shirt.
The crowd broke into deafening screams as Harry, 18, struggled to button up his top and keep his chest covered.
The pranksters later gave each other a high five and Harry a pat on the back.
VIDEO: Harry Styles supports Cancer Research UK
VIDEO: One Direction coming soon
VIDEO: Teen Now meets One Direction part 1
VIDEO: Teen Now meets One Direction part 2
VIDEO: Capital FM Jingle Bell Ball part 2 with One Direction