The status of Indianapolis Colts S Bob Sanders is uncertain for Sunday.

Sanders, who missed the first five games of the season with a knee injury, missed practice Wednesday with an elbow injury, and Colts Head Coach Jim Caldwell said Thursday the extent of the injury isn’t yet known. Caldwell said Sanders was getting the injury evaluated.

“I haven’t heard a final decree from the medical staff,” Caldwell said Thursday as the AFC South-leading Colts (7-0) prepared to play the Houston Texans (5-3) in a division game at Lucas Oil Stadium in downtown Indianapolis Sunday at 1 p.m.

Sanders sustained the injury during a victory over San Francisco Sunday.

“It did not keep him out of the game,” Caldwell said. “I’m not sure at what point in the game it happened. It didn’t flare up until a little while later.”

If Sanders can’t play, the Colts likely will return to the starting safety tandem of Melvin Bullitt and Antoine Bethea.

Colts Thursday news and notes:

* The status of WR Anthony Gonzalez (knee) remains uncertain. He missed practice Wednesday and Caldwell said he is seeking outside opinion on the knee injury that has kept him out since Week 1. “I couldn’t tell you anything definitive,” Caldwell said. “Things change rather rapidly around here. I’d rather wait until I know we have something to talk about.”

* The status of CB Marlin Jackson (knee) remains uncertain. It was thought early in the week he might practice this week and be available Sunday, but he missed Wednesday’s practice. The cornerback situation likely will be an issue the rest of the week. With Jackson and CB Kelvin Hayden (knee) missing practice Wednesday, there’s a chance rookies Jacob Lacey and Jerraud Powers will start Sunday against Houston. In that scenario, CB Tim Jennings likely will play nickel with T.J. Rushing playing as the fourth corner.

* RB Donald Brown returned to practice this week came out of Wednesday’s practice feeling good, Caldwell said. He missed last week’s game with a shoulder injury.