That means Greenlaw will not be on the field with his teammates when the 49ers host the Washington Commanders on Monday, October 19.
A suspension seemed inevitable after the incident, as the NFL classified the linebacker's actions as unsportsmanlike conduct.
Greenlaw was ejected in the second quarter after headbutting Seahawks linebacker Ernest Jones IV on the sideline. The incident was particularly dangerous because Greenlaw was wearing his helmet, while Jones was not.
Fortunately, Jones was not injured in the exchange.
"During the second quarter, Greenlaw used his helmet to headbutt Seattle linebacker Ernest Jones IV, who was not wearing a helmet, violating Rule 12, Section 3, Article 1, which applies to 'any act which is contrary to the generally understood principles of sportsmanship,'" the NFL wrote in a statement.
The altercation followed a hit by Greenlaw on Seahawks quarterback Sam Darnold after Darnold had stepped out of bounds. The play prompted Seattle players to converge on Greenlaw, escalating tensions on the sideline.
After the game, 49ers head coach Kyle Shanahan acknowledged that Greenlaw needed to exercise better judgment.
"I didn't totally see it," Shanahan said. "I was told, but that's how it is. You're going to get baited big time, especially when you're on their bench. They're going to get close.
"And they told me that he headbutted a guy without a helmet. So, if that's exactly what happened, then yeah, we've got to be a lot smarter than that. Can't do that."
Related News
Nobody's perfect. Did you find a mistake in this article? Report it.
More San Francisco 49ers News
-
49ers' George Kittle fired up about one player's potential return
On Thursday, San Francisco 49ers head coach Kyle Shanahan and quarterback Brock Purdy expressed optimism that wide receiver Christian Kirk is trending toward making his 49ers debut. That could come as early as Sunday against the Atlanta Falcons. Another player in the locker... -
Former NFL player doubts 49ers' Kyle Shanahan will ever win a Super Bowl
Former NFL wide receiver Roddy White spent his entire 11-year career with the Atlanta Falcons, including his final season in 2015, when he played in an offense coordinated by current San Francisco 49ers head coach Kyle Shanahan. White has never shied away from criticizing... -
49ers Are Finding Success With One of the NFL's Most Unusual Offenses
The San Francisco 49ers have taken a different approach to offensive personnel than most NFL teams, and their production shows just how effective that strategy has been. While most NFL offenses rely heavily on formations featuring three wide receivers, San Francisco has built... -
ESPN proposes 49ers trade for Colts DT—but not the one you think
ESPN's Bill Barnwell has proposed a trade that would send a defensive tackle from the Indianapolis Colts to the San Francisco 49ers. However, it's not the player many fans might expect. There's been plenty of speculation about DeForest Buckner returning to the team that...