RENTON, Wash. - Already hampered by two major season-ending knee injuries on the offensive line, the Seahawks lost left tackle Russell Okung for the rest of the season on a play Seattle coach Pete Carroll called "out of line" on Friday.

Okung suffered a torn pectoral muscle late in Seattle's 31-14 win over Philadelphia on Thursday night. Okung's injury cast a cloud over a night highlighted by Marshawn Lynch's 148 yards rushing and two touchdowns, the second-best performance of his career.

Okung got thrown by Philadelphia defensive end Trent Cole away from the play inside the final 2 minutes and after the whistle had blown. Okung underwent tests Friday to determine the severity of the injury. During his midday news conference, Carroll called it "significant" and the Seahawks announced the results of the injury later Friday. Okung is likely headed for surgery and a long rehabilitation.

When asked if it was a dirty play Okung was hurt on, Carroll said it was "a bad play."

"He got grabbed under the arm and thrown down to the ground. It had nothing to do with the play. It wasn't a late hit," Carroll said. "It might look like he was trying to disengage and that might be what they say and all, but it was really late and it was really out of line unfortunately."

Okung is the third Seahawks starting lineman to go down if he is done for the year. The Seahawks (5-7) lost the entire right side of their line last month when rookies John Moffitt and James Carpenter went down with knee injuries that required surgery. Moffitt was hurt in Seattle's win over Baltimore, while Carpenter was lost when he tore his ACL during practice just a few days later.

Now comes Okung's latest injury after he was slowed during his rookie season a year ago by continued ankle problems, but had stayed healthy and played well for most of his second season.

The injury came on the first play after the 2-minute warning with Seattle holding its big lead. Okung and Cole engaged on a running play to Leon Washington that went to the right side. On the television broadcast, Okung appears to let up as the whistle blows, then gets flung over Cole's hip and to the ground.

Okung had to be restrained and pulled away from Cole after the game ended. He was holding his arm gingerly in the locker room after the game.

Seattle does get a few days to figure out how to approach the possible loss of Okung. Carroll gave his team Friday through Monday off, with the Seahawks returning to practice Tuesday in preparation for their Monday night game on Dec. 12 at home against St. Louis.