In the top of the ninth with two outs, Prado chased the ball fouled off towards the third base stands by Giants batter Joe Panik. Prado ran full speed towards the stands and his face smacked into the forehead of a fan in the front row. The ball landed just out of reach of Prado behind the first row. Fortunately, both Prado and the fan appeared to be OK.
To add insult to injury, however, Panik ended up hitting a double and knocking in a run. The Giants beat the D-backs 4-1.
Video via MLB.