The Carolina Panthers placed Stephen Davis on injured reserve on Saturday, their third running back to be lost for the season.
Davis has played in just two games this season after arthroscopic surgery Sept. 17 to clean out torn cartilage from his knee. He's tried to get back on the field several times since, but his knee would swell after every practice.
He now joins backup running back DeShaun Foster (broken collarbone) and third-stringer Rod Smart (knee) on the injured list. In all, Carolina (1-7) has 11 players out for the year.
But they're hardest hit in the backfield, where rookie Joey Harris started last week after beginning the season on the practice squad. But he pulled his hamstring on Friday and is questionable for today's game against San Francisco.
Carolina signed former 49ers running back Jamal Robertson on Saturday.
Davis, meanwhile, goes from the best season of his career to the worst.
He ran for a career-high 1,444 yards last season while leading the Panthers into the Super Bowl. But this year he has just 24 carries for 92 yards this season for the Panthers.
He played in the season-opener against Green Bay, had surgery four days later, and returned to play against Philadelphia. He has practiced sporadically since.
Robertson has appeared in 22 contests in three NFL seasons, all with San Francisco, and has totaled 207 yards rushing and one touchdown on 48 attempts. He saw action in seven games this year and led the 49ers with a 22.4-yard kickoff return average to go along with 71 yards rushing and 34 yards receiving before being waived on Nov. 2.
STEELERS RELEASE BACKUP: The Steelers released quarterback Brian St. Pierre on Saturday and called up Dante Brown from the practice squad to give them more strength at running back.
Brown, a second-year player from Memphis, has spent the 2004 season on the Steelers' practice squad. He played in two games last year.
The Steelers are thin at running back, with third-down back Verron Haynes (turf toe) doubtful and Duce Staley questionable with the sore hamstring that kept him out of the 27-3 victory over Philadelphia.