The Panthers placed fullback Mike Tolbert on injured reserve, with the designation to return Tuesday, meaning the Pro Bowler will be out a minimum of two months.
Tolbert has a hairline fracture in his left leg below his knee, but will not require surgery, according to a league source.
Teams may use the so-called "short-term" injured reserve only once during the season, and the designated player is not eligible to play for a minimum of eight weeks.
Tolbert, who went to the Pro Bowl last season after leading the Panthers with seven total touchdowns, can rejoin the active roster Nov. 18, which falls during the team's bye week. The Nov. 30 game at Minnesota would be the earliest game Tolbert could play.
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Rather than sign a running back to fill Tolbert's roster spot, the Panthers re-signed linebacker D.J. Smith, who started the season on Carolina's practice squad before his Sept. 3 release.
The signing of Smith signals some concern over the health of veteran linebacker Thomas Davis, who left Sunday night's loss to Pittsburgh with an apparent left knee injury.
Panthers coach Ron Rivera would not specify Davis' injury Monday when meeting with reporters, other than to say it was not "catastrophic" and did not involve his right knee, which has undergone three ACL surgeries.
Tolbert is the latest injury to the Panthers' running backs. DeAngelo Williams missed the past two games with a hamstring issue, but is expected to practice this week, according to Rivera.
Jonathan Stewart, who missed about half the past two seasons with injuries, has a severely sprained right knee that has left his status for this week's game at Baltimore in doubt.
Fourth-string running back Fozzy Whittaker sat out the Steelers' game with a quad injury.
The Panthers also have two rookie running backs: Darin Reaves was activated from the practice squad last weekend, while Lache Seastrunk was recently added to the practice squad.