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

Clowney visited Dr. James Andrews in Pensacola, Fla., on Wednesday to have the knee examined and coach Bill O'Brien announced the news yesterday.

"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 and said last week that he's still in a lot of pain.

O'Brien lauded the 21-year-old for trying to fight through this injury and stay on the field. He saw his most extensive action of the season against the Bengals on Nov. 23 when he was in for about 50 plays and had three tackles, including one for a loss. But he experienced swelling in his knee after that and missed his eighth game of the year last week.

"He's a tough kid," O'Brien said. "He tried to go out there and play in the Cincinnati game. He came back in the first Tennessee game - he really wanted to play. He really wanted to be out there for his teammates. But at the end of the day he wasn't able to do the things that he really wants to do to be the player that he can be."

O'Brien wouldn't give details of Clowney's surgery or when it will be performed. Clowney didn't speak to the media on Thursday, but O'Brien talked about how he's dealing with his latest setback.

"He wants to play football. He wants to be good so I think he was disappointed right off the bat," O'Brien said. "But I think he understands what he has to do and why this is necessary and he knows that he has to rehab hard and get back out there."

Clowney has had a difficult time since Houston took him first in this year's draft, eager to put him on a defense already featuring rush specialist J.J. Watt. 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.

Houston will continue relying on Whitney Mercilus to fill in for Clowney on Sunday at Jacksonville. Mercilus, who was the 26th pick in the 2012 draft, has started 10 games this season and has 43 tackles, four sacks and a forced fumble.

"Whitney has really done a good job this year," O'Brien said. "He's a very improved player . . . I think this guy has worked extremely hard to try to become a better player. I think you've seen that on the field."

Noteworthy

* Baltimore 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 released by the team that he took Adderall. "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.

* Atlanta safety William Moore says he has been fined $22,050 by the NFL for a crown-of-helmet hit on Arizona wide receiver Jaron Brown last week.

* Offensive coordinator Greg Roman says he has moved on from a critical Twitter post last week by the daughter of his boss, 49ers general manager Trent Baalke. After a 19-3 loss to the Seahawks last Thursday, Cassie Baalke called for Roman to be gone before quickly deleting her tweet and later shutting down her account altogether. "Greg Roman can take a hike..the 49ers don't want you no more," the tweet read. After her words were icons of hands clapping. Trent Baalke said last Friday that both he and his daughter had apologized to Roman.

* Pittsburgh quarterback Ben Roethlisberger, who hit his right (throwing hand) on a New Orleans player Sunday and skipped practice Wednesday, "was sharp" in team drills, according to offensive coordinator Todd Haley.

* The New York Jets placed wide receiver Greg Salas on season-ending injured reserve with a hamstring injury and signed wide receiver Chris Owusu from the practice squad. Also, coach coach Rex Ryan said team trainers are happy with the progress Muhammad Wilkerson is making with his turf toe injury, but acknowledged that the defensive end will miss his second straight game.

* Tennessee coach Ken Whisenhunt said receiver Kendall Wright hurt a hand on a route Wednesday, so they gave him the day off to rest it. Wright wore a splint on the hand during the open portion of practice, and Whisenhunt says they should know more about the injury today with an X-ray planned.

* Pro Bowl receiver Andre Johnson says he wants to finish his career in Houston and has moved past whatever bad feelings kept him away from the team for much of this offseason.

* Adrian Peterson's appeal hearing concluded in New York after about 2 hours yesterday, with the primary focus on testimony from NFL executive Troy Vincent, a source told the Associated Press. Peterson is seeking reinstatement after NFL commissioner Roger Goodell suspended him for the final six games of the regular season for violating the league's personal conduct policy..