One Direction's Niall Horan is in "a lot of pain" after an object struck him in the knee during a concert in Amsterdam.

Niall was caught on camera by a fan during the Where We Are Tour stop on Thursday hobbling across the stage clearly favoring his knee, on which he had surgery back in January.

Shortly after the show, Niall took to Twitter to thank the Amsterdam crowd for their support, but to kindly ask them to stop throwing things onstage.

The hashtag #feelbetterniall trended on Twitter, with more photos going around of the incident. It appears that a shoe struck Niall, ripping his pants, and causing his knee to bleed. Ouch!

this should be a lesson for people who are throwing things to the boys during their shows #FeelBetterNiall pic.twitter.com/0obbFTXREQ

— Niall Horan (@itshorancrew) June 26, 2014

But Niall wasn't the only one struck by flying objects, Harry also caught a pretty hard shot to the face, but shook it off and kept on singing.