The Kaiser Chiefs set started on a high, and two numbers in went higher, lead singer Ricky Wilson climbed the scaffolding at the side of the stage and towards the end of the number climbed back down, dropped a few feet and then ran across the stage and fell over. It's not clear if Ricky hurt his right ankle when jumping down or when he was running across the stage, but he couldn't put any weight on in for the rest of the act.
He didn't let it "hurt" his performance and the chiefs were great. Good news is they'd already cancelled the rest of the US tour through fatigue, so Ricky can rest up, it's only rock and roll!
See their opening number, before the injury!