What happened: Officials ejected San Francisco 49ers linebacker Dre Greenlaw from Sunday's game against the Seattle Seahawks after he headbutted linebacker Ernest Jones IV. The incident occurred on the sideline in the second quarter, with Greenlaw striking Jones while the Seattle defender was without his helmet.

Why it matters: The disqualification removes a core member of San Francisco's defense for the remainder of a divisional matchup. Greenlaw's early exit forces the 49ers to rely on their linebacker depth for the rest of the contest.

What to watch: The NFL will review the sideline incident for potential supplemental discipline or fines.