Sources: Chris Clemons feared lost

The Seattle Seahawks fear defensive end Chris Clemons tore his ACL during Sunday's NFC wild-card win against the Washington Redskins, league sources told ESPN NFL Insider Adam Schefter.

Clemons will undergo an MRI on Monday to confirm the injury.

Seattle's best pass-rusher, Clemons hurt his left knee in the third quarter of Sunday's game and did not return.

"We're concerned about it," Seahawks coach Pete Carroll said after his team's 24-14 comeback win.

Losing Clemons, 31, would be a significant blow to a Seattle defense that ranked No. 1 during the season with 15.3 points allowed per game.

The ninth-year veteran had 11.5 sacks during the regular season, tied for ninth-most in the league. Clemons also had 40 total tackles, three forced fumbles and a fumble recovery.

Seattle, the fifth seed in the NFC, visits the top-seeded Atlanta Falcons in the divisional round next Sunday.

Information from ESPN NFL Insider Adam Schefter and The Associated Press was used in this report.