Harrison had arthroscopic knee surgery on Aug. 15 and didn't play in any preseason games, nor has he seen the field in either of the Steelers' first two regular season games. Its unclear when the five-time Pro Bowler and the 2008 NFL Defensive MVP will be ready to play. Chris Carter started in Harrison's spot in the first two games of the season, but Jason Worilds is likely to play the majority of snaps as his wrist injury is improving.
Safety Troy Polamalu is also expected to miss his second consecutive game with a calf injury.
On the plus side for Pittsburgh, the injuries are well-timed, if there can be such a thing: neither seemed necessary last week against the New York Jets, who only managed ten points, this week's matchup is against the Oakland Raiders, against whom they are expected to win even without the defensive pair, and they have a bye week next week to give both players time to mend their injuries.