HOUSTON — The Houston Texans placed cornerback Dunta Robinson on the physically-unable-to-perform list today as they trimmed the active roster to 75 players.

Robinson has been recovering from a severe right knee injury he suffered Nov. 4, and being placed on the PUP list means he must sit out at least the first six weeks of the regular season.

"It was a hard decision because I know how hard he's working to get back," general manager Rick Smith said. "The smart thing for us to do and for him is to do it this way and to give him that extra time and make sure when he, in fact, comes back on the field, that he is ready to go."

The Texans also cut receiver Tim Carter and offensive lineman Mark Fenton, and placed receiver Harry Williams and offensive tackle Scott Jackson on injured reserve.

Williams underwent surgery on Sunday to repair a cracked vertebra he suffered in the Texans' preseason loss to Dallas on Friday, and team doctor Walter Lowe said Williams probably would never play football again.

Smith said the 29-year-old Jackson, who also spent last season on injured reserve, has a lingering left foot injury.

"He had struggled all training camp," Smith said. "We tried to treat it and just last week, we realized it was a little worse off than what we thought."

On Monday, the Texans announced they had cut fullback Jameel Cook and signed fullback Jon Abbate. The 29-year-old Cook was arrested on a misdemeanor drug possession charge after a sheriff's deputy allegedly found two grams of marijuana in his car during a traffic stop. Cook's attorney says he is innocent.

The Texans wrap up their preseason against Tampa Bay on Thursday night, two days before NFL teams must reduce their active rosters to 53 players.

"You go back and look through the years, it's amazing how many kids have made a team on the last game," coach Gary Kubiak said. "There have been players who lose jobs because of that game. The thing we want to do is get them on the field, be able to look at plays and evaluate those kids without having to make those decisions strictly off practice."

Kubiak said he'll play mostly reserves in Thursday's game. He said he would decide Wednesday who will play and for how long.

Smith said there is still competition at several positions and that he won't keep players, even established veterans, just to fill roster spots.

"Guys know what their positions are on this team," Smith said. "I don't believe in just bringing camp bodies in, so I would like to think that every guy in that locker room feels like they have a legitimate opportunity to make our club. I hope there are a bunch of guys feeling like they have to perform on Thursday, just like they have to do every time they step on the field."