Los Angeles Rams linebacker Clay Matthews will be sidelined for four to six weeks after breaking his jaw, coach Sean McVay told reporters on Friday.

Matthews will undergo surgery, according to McVay. “That’s not good for us,” the coach said. “That’s a big injury.”

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Matthews sustained the injury on Thursday during Los Angeles’ 30-29 loss to the Seattle Seahawks.

McVay says he believes it occurred when Seattle running back Chris Carson inadvertently kicked Matthews in the face.

Matthews, 33, was off to a strong start in his first season with the Rams.

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He has six sacks, two forced fumbles and 19 tackles in five games.

Matthews, who spent his first 10 NFL seasons with the Green Bay Packers, has 89.5 career sacks in 148 games (142 starts).

Rams receiver Brandin Cooks (concussion) also was injured and was placed in the NFL protocol.