Robert Griffin III sustained a knee sprain in the Washington Redskins' win over the Baltimore Ravens yesterday.
The Redskins quarterback limped off in the fourth quarter after bending his leg awkwardly during a tackle from Haloti Ngata.
After the game, the rookie said: "I was trying to make a play, and as soon as I turned it inside, I said, 'Oh Lord, here we go'.
"It was a freak play, my leg got hit after I was already down. It was pretty painful. Just praying that I'll be all right.
"I'm not a doctor, but I know what an ACL feels like, and it doesn't feel like an ACL. [The doctors] said my ligaments feel good, but it depends on what the MRI says. I'm feeling positive vibes from them and from the team."
Washington later confirmed that the scan came back clear.