A participant in a sporting event has landed on his head while holding the ball on a field of grass .
There is a better than even chance that a football player has hit his head on the ground during a game .
There is a better than even chance that a football player has hit his head on the ground during a game .
There is almost no chance that a football player has hit his head on the ground during a game .
A football player has hit his head on the ground during a game .