Although he didn't practice all week, Mathews was placed on the active list after a brief pregame workout Sunday, with San Diego's training staff watching every move.
Mathews has not missed a game all season for the first time in his four-year professional career. He has been dealing with the ankle issue since suffering the injury in the second half of San Diego's game against Oakland on Dec. 22.
Mathews finished with 52 yards on 13 carries in last week's AFC wild card win over the Cincinnati Bengals. But he only carried the ball once time in the second half, giving way to Danny Woodhead and Ronnie Brown.
Mathews was held out of practice this week in an effort to rehabilitate his ankle as long as possible before playing against the Broncos.
Mathews will be running behind his team's seventh different offensive line combination this season, as right guard Jeromey Clary has been placed on the inactive list due to a shoulder injury.
Right tackle D.J. Fluker also is nursing an ankle issue, but is active and will start. Center Nick Hardwick (concussion) and receiver Eddie Royal (toe) also were questionable heading into this weekend, but will be active.