In his NFL regular-season debut Sunday, former South Carolina defensive end and Houston Texans 2014 No. 1 pick Jadeveon Clowney suffered a knee injury coming off the edge late in the second quarter and did not return. Visibly frustrated while limping toward the sideline, Clowney was examined by team personnel before heading into the locker room.

“I don’t know what happened on the field,” Texans coach Bill O’Brien said after the game. “I’m not sure what happened on that one. We’re consulting with the doctors and trainers right now. I’m not sure about the status, but I will say right now that they think it’s a good prognosis so it looks like it’s going to be ok. He may miss some time, he may not. Who knows. We’ll know better as the week goes on.”

According to The NFL Network’s Albert Breer, Clowney landed awkwardly after leaping in pursuit of Redskins quarterback Robert Griffin III. Earlier in the game, Clowney stopped Washington wideout Desean Jackson in his tracks on a reverse for a nine-yard loss.

Clowney looked mighty impressive during the preseason as an outside linebacker and rush end for the Texans and is expected to be an instant impact player as a rookie. Further tests on Monday will determine if there’s ligament damage.

NFL insider Adam Schefter reported Sunday that team officials fear Clowney may have suffered a meniscus tear which would require surgery.