Marshawn Lynch will miss a second straight week for the Seattle Seahawks due to a hamstring strain.
The team on Friday officially ruled Lynch out for Sunday's game against the Cincinnati Bengals.
Lynch injured his hamstring in the second quarter of the team's 26-0 victory over the Chicago Bears in Week 3. Lynch returned to limited participation in practice on Thursday but is not ready to return. He will not travel with the team to Cincinnati.
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"He could try to come back and play but we think he'd be vulnerable," Seahawks coach Pete Carroll said. "He needs another weekend to get through it and then by next week, by Wednesday or something, we think we can get him going again. We're just about over the hump."
Backup Fred Jackson is listed as questionable after suffering a high-ankle sprain last week against Detroit. Carroll was optimistic that Jackson would be able to play.
"We're thinking he's going to make it," Carroll said. "He'll have to work out on game day but he looks really good and we think he's going to play."
Carroll said the team may need to make a roster move to add running back depth before the game. Rod Smith would be the likely option to be elevated from the practice squad.
Cornerbacks Tharold Simon and Marcus Burley have also been ruled out for Seattle. Simon has a dislocated toe that isn't healing properly.
"Nature has given him a toe that's got some issues and we've just got to work through it," Carroll said. "He's had surgery on his other foot -- same toe, same situation -- so that's something we're trying to work through right now to see if that's necessary or not."
Burley suffered a broken thumb last week against the Lions and had surgery on Thursday. Carroll said Burley should only miss around three weeks.