The San Francisco 49ers have lost a key member of their talented defense after placing linebacker Parys Haralson on injured reserve.
San Francisco also signed linebacker Clark Haggans to a one-year contract to help fill the void as the defending NFC West champions prepare for Sunday's season opener at Green Bay.
The Niners announced the roster moves Monday without providing details on Haralson's injury, though he is believed to have hurt his left arm during the first half of a preseason win at Denver on Aug. 26. He didn't play in Thursday night's exhibition finale, a 35-3 win over the Chargers.
Haralson had been among the 11 returning starters for 2012 on Vic Fangio's defense that ranked No. 1 at stopping the run during a resurgent 13-3 season.