Top overall pick Jadeveon Clowney will have a second surgery on his right knee, ending his rookie season for the Houston Texans after just three games.

Coach Bill O'Brien announced the news Thursday, after Clowney's knee was examined by James Andrews in Pensacola, Fla., on Wednesday.

"This guy's been injured, and it's time to clean it up and get him back to feeling good and get him back on the field as soon as we can," O'Brien said.

The outside linebacker was injured in Week 1 and had arthroscopic surgery Sept. 8. He has played three games since then but has never completely recovered from the procedure. He said last week that he's still in a lot of pain.

Receiver Andre Johnson, who wondered in the offseason whether Houston "was still the place for me," now says he wants to finish his career with the Texans. "I don't want to play for nobody else . . . . I don't even think it would feel right," he said.

4-game ban for Ngata

Ravens defensive tackle Haloti Ngata was suspended without pay for four games for violating the NFL's policy on performance-enhancing substances.

Ngata will miss the rest of the regular season but will be eligible for the playoffs, the league said.

Ngata said in a statement that he took Adderall, a drug used to treat attention deficit hyperactivity disorder.

"I made a mistake, and I own this," he said.

Ngata has two sacks, two interceptions, and two forced fumbles in 12 games this season.

Redskins challenged

One of coach Jay Gruden's biggest disappointments this season is that there are "too many blown assignments."

So, the rookie head coach has challenged his team. He wants to see smarter football the rest of the season, saying his players need to make the upcoming schedule the "most important four games of their careers."

The 3-9 Redskins will host the Eagles on Dec. 20 and also will face the Rams, Giants, and Cowboys.