There is a reason why rugby players don't tackle head first.
This spectacular head clash happened in the NRL game between the Cronulla Sharks and the Sydney Roosters. Michael Ennis of the Sharks came off worse, in a moronic head-first tackle on Roger Tuisava Sheck.
Ennis is a new recruit to Cronulla, and was forced off after the incident which left his head pouring with blood. Somehow Ennis was allowed return as the Sharks managed to pull of a shock 20-12 over the Roosters.
https://www.youtube.com/watch?v=KUKhGROQyOU