HOUSTON — Houston’s Jadeveon Clowney, the top overall pick in this year’s draft, injured his knee Sunday and didn’t return against Washington.

Coach Bill O’Brien didn’t provide much more information on Clowney’s health after the game.

“They think it’s a good prognosis, so it looks like it’s going to be OK,” O’Brien said. “He may miss some time, he may not. Who knows? So we’ll know better as the week goes on.”

It wasn’t clear how Clowney was injured, but it happened late in the second quarter. He looked to be arguing with the team doctor as the pair walked off the field to the locker room a couple of minutes before halftime.

Clowney has struggled to stay on the field since joining the Texans. He left a dual practice Aug. 20 after a helmet-to-helmet hit with Denver Broncos tight end Jacob Tamme. He missed the Texans’ final two preseason games, but said he passed the NFL protocols for head injuries in just over a week. He had to sit out the beginning of camp, too, after offseason surgery to repair a sports hernia.

RAMS

Quarterback Hill sidelined with thigh injury: In St. Louis, Rams quarterback Shaun Hill left the game against the Vikings with a thigh injury. Austin Davis replaced him to start the second half, making his NFL debut.

It was unclear how Hill was hurt. He stood on the sideline far away from play, arms folded.

The 34-year-old Hill made his first start since 2010 in place of Sam Bradford, lost for the season with a left knee injury in the third preseason game.

Davis has been with the Rams for parts of three seasons. He backed up Kellen Clemens the last nine games last season.

Hill was 8-for-13 for 81 yards and an interception by Josh Robinson that set up a Vikings touchdown for a 13-0 lead in the final minute of the half.

BENGALS

Linebacker Burfict leaves with head injury: In Baltimore, Cincinnati Bengals linebacker Vontaze Burfict left Sunday’s game against the Ravens with a concussion.

The play occurred late in the first half when Burfict hit his head while putting pressure on quarterback Joe Flacco.

Burfict left the field after a short delay and was declared out for the game early in the third quarter.

At the time, Burfict had four tackles and knocked away a pass.

Burfict made the Pro Bowl last year and was Cincinnati’s leading tackler with 204. He also had three sacks.