HOUSTON -- Mario Williams, the Houston defensive end who went to the last two Pro Bowls, is out for the rest of the season.

The Texans said Wednesday that Williams, the first overall pick in 2006, had been placed on season-ending injured reserve. He's struggled with injuries since September, and a groin injury was listed as the reason.

Coach Gary Kubiak said Williams will have surgery to repair a sports hernia on Tuesday in Philadelphia.

"You've just got to do what's best for Mario," Kubiak said. "I'd have loved for him to be able to hang in there and give us 20-25 plays a game the rest of the way, but he just wasn't getting better. It was getting worse and the last two weeks have been the worst. The doctors just feel like he needs to get this fixed right away."

Williams has started every game in his career, 77 straight. He has 28 tackles, 8½ sacks and a forced fumble this season.

"Mario is a tough guy, gives his team everything he has," Kubiak said. "Even when he's not 100 percent, he's a dang good player. So there's a lot to be said for what he's been doing and especially what he did this year."

Williams wasn't available for comment Wednesday.

His teammates knew he had been struggling with the injury for a while, but fellow defensive end Antonio Smith realized it had gotten worse during Monday night's loss to Baltimore.

"He was fighting and you could just tell that he was in a lot of pain," Smith said. "It was hard to play with. It hindered him in this last game to the point where I knew it was something seriously wrong. After one play he just stopped and ... said: 'Man I think something's really wrong.'"

Tim Jamison, who has appeared in seven games this season, will get the majority of playing time in place of Williams, but Kubiak said a combination of people will fill his role.

The team also placed wide receiver David Anderson (shoulder) and guard Mike Brisiel (calf) on injured reserve. The Texans signed receiver Derrick Townsel from the practice squad to the active roster and added defensive tackle DeMario Pressley to the active roster from the New Orleans Saints' practice squad.

Houston signed receiver Montez Billings and center Brett Helms to the practice squad.

The Texans (5-8) play at Tennessee (5-8) on Sunday. If AFC South rival Jacksonville wins just one of its last three games, Houston will be eliminated from postseason contention for the ninth straight year.