Mike Shanahan has been defending his decision to leave Robert Griffin III on the field against the Seattle Seahawks despite being injured.

The Washington Redskins quarterback aggravated a knee sprain during the playoff game, and was unable to finish the fourth quarter.

The Washington head coach told reporters: "I think everybody could see after the first quarter that he wasn't always exactly the same, but I got a lot of players that aren't exactly the same, there's not a lot of quarterbacks that are exactly time this time of year.

"Robert said to me, 'Coach, there's a difference between injured and being hurt. I can guarantee I'm hurting right now, give me a chance to win this football game because I guarantee I'm not injured.' That was enough for me.

"I still thought he could go in there and make the plays he was capable of making against an excellent defense. I'll probably second-guess myself when you take a look at the second half, should have I done it earlier? I think you always do that, especially after you don't win."

RG3 is due to undergo an MRI scan today to assess the extent of the injury.