THOUSAND OAKS, Calif. -- Los Angeles Rams outside linebacker Clay Matthews will be sidelined for an extended period because of a broken jaw suffered in a 30-29 loss to the Seattle Seahawks, Rams coach Sean McVay said Friday.

"That's not good for us," McVay said. "That's a big injury."

Rams receiver Brandin Cooks also has been placed into concussion protocol after he left the game in the fourth quarter Thursday night. McVay said Friday that Cooks was asymptomatic.

Matthews declined a postgame interview Thursday night, citing a sore jaw. McVay said he would undergo surgery and that he was uncertain for how long Matthews would be out.

"I know it's going to be at least a month," McVay said.

McVay said Matthews was kicked in the jaw by Seahawks running back Chris Carson on a tackle near the end of the game.

"It was a physical game," McVay said.

Matthews finished with a sack and four tackles. He also drew a penalty in the fourth quarter for roughing quarterback Russell Wilson.

Outside linebacker Samson Ebukam replaced Matthews and will take over as the starter in his absence. A third-year pro, Ebukam started last season and had three sacks and three forced fumbles.

The Rams signed Matthews, an 11th-year pro, to a two-year, $9.25 million contract over the offseason. In five games, he has six sacks, two forced fumbles and a pass deflection.

"It's going to be a big loss," McVay said.