Mathews will miss his third straight game with what's believed to be a high ankle sprain. He was hurt during a home loss to New England on Dec. 7.
Also ruled out on Friday was punter Mike Scifres, who broke his left collarbone in the loss to New England.
Wide receiver Keenan Allen is listed as doubtful with a broken right collarbone and is expected to miss his second straight game.
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