The San Francisco 49ers were significantly undermanned by the end of their 28-18 Week 7 loss to the Kansas City Chiefs.

Not only did they lose Brandon Aiyuk and Deebo Samuel to a knee injury and an illness respectively, they also lost left tackle Trent Williams after he was ejected in the fourth quarter.

Williams’ ejection occurred with 3:03 left in the contest. The veteran offensive lineman was on the ground when Chiefs safety Bryan Cook came over to him and took a swipe at his facemask.

Williams responded by hopping to his feet and taking a big shot at Cook. He punched Cook in the back of the helmet, drawing a flag and resulting in his dismissal from the game.

The NFL considers punch to be a “prohibited act,” which is viewed as a form of unsportsmanlike conduct, per the league’s rulebook. NFL officials are allowed to disqualify players for “flagrant” acts if seen by the on-field officials or replay official, which explains why Williams was ejected from the game.

Cook was not penalized for his role in the incident. It isn’t clear if the officials didn’t see his swipe at Williams or if they didn’t view it as flagrant enough to warrant an ejection or flag.

Either way, Cook remained in the game after the tiff and was unharmed after absorbing the blow from Williams.

Tempers had already flared in the 49ers vs. Chiefs game after Kansas City receiver Skyy Moore and San Francisco cornerback Deommodore Lenoir got into a shoving match following Mecole Hardman’s fourth-quarter touchdown. Cooler heads prevailed after Williams’ ejection, and there were no further tussles in the final three minutes of the Super Bowl 58 rematch.