Tests on the left knee of Chris Clemons confirmed that the Seattle Seahawks defensive end tore his anterior cruciate ligament and injured the meniscus during Sunday's victory against the Washington Redskins.
Clemons will undergo season-ending surgery, coach Pete Carroll announced Monday.
"A big loss for us in a lot of ways," Carroll said. "Chris has been a great football player, just a symbol of consistency for the years we've had him. But he's been a great leader for us and a tough dude, and a guy we just have become very comfortable with."
Clemons leads the Seahawks with 11.5 sacks, and his absence likely will mean first-round pick Bruce Irvin will move from the left side to the right side on passing downs. Irvin has been a situational pass rusher.
Greg Suggs, a rookie out of Louisville, also figures to see increased snaps in Clemons' absence. He was active for 11 games during the regular season, recording six tackles and a pair of sacks.
Henderson believes the conditions at FedEx Field contributed to the injury. Clemons was wearing three-quarter-inch cleats to get traction on the slippery surface.
Carroll said the team also will consider bringing in kickers for tryouts this week in case Steve Hauschka is unable to play at the Atlanta Falcons on Sunday due to a strained left calf. Hauschka's calf was improved Monday, according to Carroll.