Miami Marlins pitcher Dan Jennings barely had time to register his pitch before it was fired straight back at his head.

The ball, which reached almost 150kmh, rocketed off Jennings, leaving him stumbling and visibly concussed.

Though hats to protect pitchers have been designed, almost none of the players in Major League Baseball choose to wear them.

Jennings was immediately brought to a nearby hospital to receive medical attention, though thankfully he has been given the all-clear.

The scans were negative-it seems I'm going to be ok. The support shown tonight has been unbelievable, speechless. God is amazing

— Dan Jennings (@LtDanJennings) August 8, 2014