Polamalu also might miss the Steelers'
Nov. 29 showdown with the AFC North rival Baltimore Ravens, NFL Network's Jason La Canfora reports, citing a league source. The Steelers are hopeful the injury will not keep Polamalu out of more than three games total, according to La Canfora, and the team will be cautious about how quickly the five-time Pro Bowl safety returns.
Polamalu's latest injury is to a different ligament. He wore a heavy brace as he watched practice this week.
Defensive end Travis Kirschke will sit out his third consecutive game for the Steelers because of a torn left calf muscle. He had been filling in for Aaron Smith, who's out for the season with a torn right rotator cuff.
Nick Eason will start again at left defensive end. Tyrone Carter will start at safety in Polamalu's place.
The Associated Press contributed to this report.