ALLEN PARK — Cornerback Chris Houston, who has practiced on limited basis for three days, is listed as doubtful for Sunday’s game at the San Francisco 49ers on the Friday injury report.

Houston has not played since he sustained a high ankle sprain in the Aug. 25 preseason game.

“We’ll see when we get to Sunday what he can do and everything else,’’ coach Jim Schwartz said after Friday’s practice. “See how he can help and, if he can, then we’ll put him on the field. If he can’t, we won’t. He is valuable to our defense and I think he does have a calming influence.’’

Also listed as doubtful are Louis Delmas (knee) and Travis Lewis (quad). Delmas hasn’t practiced since Aug. 7 surgery while Lewis sat out all week after injury in the opening game.

Defensive tackle Corey Williams (knee) did not practice this week but is listed as questionable along with defensive end Lawrence Jackson (calf) who returned to practice on Friday.

Cornerback Bill Bentley, who sustained a concussion in the win over the Rams, is listed as out. He has not been cleared for contact.

If Houston doesn’t play look for Jacob Lacey and Drayton Florence to start.

At safety Erik Coleman and John Wendling started last week and should get the nod again.

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