"The availability of safety Bob Sanders for the Indianapolis Colts' regular-season opener remains in doubt.

Sanders is on the physically unable to perform list after undergoing surgery on his right knee during the offseason. He missed 10 games in 2008 after having surgery on the same knee.

"I'm not certain,'' coach Jim Caldwell replied this morning when asked if he was confident Sanders would be ready for the Sept. 13 opener against Jacksonville. "I would say that if I felt that way. I'm really not certain.

"The most important thing is to get him healthy.''

The team recently discussed Sanders' situation with its own doctors and James Andrews, the noted orthopedic surgeon who performed Sanders' surgeries."