The 49ers lead the Seahawks 14-10, but they will have to play the rest of the game without linebacker Dre Greenlaw.
Greenlaw was ejected with 6:04 remaining when he headbutted a helmetless Seahawks linebacker Ernest Jones IV on the sideline.
Greenlaw forced Sam Darnold out of bounds after a 5-yard scramble, putting him in the middle of the Seahawks sideline. Jones said something to Greenlaw, who headbutted Jones.
The 15-yard penalty moved the Seahawks to the San Francisco 32.
Greenlaw was ejected during a Dec. 3, 2023, game against the Eagles when he scuffled with Eagles chief security officer Dom DiSandro.
Last week, the NFL fined Greenlaw $11,941 for taunting the Broncos' sideline.
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