South Korean cyclist Park Sang-hoon had to be taken from the track on a stretcher wearing a neck brace after a huge crash in Monday's omnium points race in the velodrome.
Park was caught up in a tangle with Mark Cavendish as the Great Britain rider looked to claw back enough points to win a medal. The Briton ultimately finished with silver.
The South Korean was left helpless as Cavendish cut across him, with leader Elia Viviani also hitting the boards in the crash.
The Italian was able to continue, after the race was neutralised, and held on to clinch gold.