Robert Griffin III left the Washington Redskins' 24-17 loss to the Atlanta Falcons in the third quarter with a mild concussion after taking a hit to his head, coach Mike Shanahan said after Sunday's game.
The Redskins initially said their rookie quarterback was "shaken up" and questionable to return, although Griffin didn't play in the game again.
"When he really wasn't sure what quarter it was, what score it was, we knew he had a mild concussion, at least according to the doctors," Shanahan said.
"(He) feels good right now, a lot better right now," the coach added. "But that was the situation why he didn't go back into the game."
Griffin was hit in the head after improvising a rollout outside the pocket on third-and-goal with 6:22 remaining in the quarter. Instead of throwing the ball away, RG3 slid and took a massive shot from Atlanta Falcons linebacker Sean Weatherspoon, who hit the quarterback with his shoulder.
RG3 cut his lip on the play and appeared to be mouthing "I'm fine" to Shanahan after the play. The quarterback then went to the locker room to be evaluated, at which point a neurologist diagnosed him with a mild concussion.
Follow Gregg Rosenthal on Twitter @greggrosenthal.