Up above, video of Bryce Harper's head meeting Eric Young's shin during the second inning on Opening Day. The good news is: Harper reportedly passed two concussion tests and only has a headache:
"I feel all right. It was his knee or his shin, he kind of blew me up a little bit. I feel okay now. I just got a pretty bad headache, things like that. No haziness or dizziness. That’s a plus. But my head hurts pretty bad right now."
(Bryce Harper, via Nats Insider, 3/31/2014)