The NFL has suspended Detroit Lions safety Brian Branch for one game without pay following an on-field altercation with Kansas City Chiefs wide receiver JuJu Smith-Schuster that escalated into a brief fight during Sunday night’s matchup.

In announcing the decision Monday, NFL vice president of football operations Jon Runyan cited Branch for unsportsmanlike conduct, saying his actions were “entirely unwarranted” and posed “a serious risk of injury.”

“Your aggressive, non-football act was entirely unwarranted, posed a serious risk of injury, and clearly violated the standards of conduct and sportsmanship expected of NFL players,” Runyan wrote in a letter to Branch. “Your conduct reflected poorly on the NFL and has no place in our game.”

A source confirmed to ESPN’s Jeremy Fowler that Branch plans to appeal the suspension. The appeal will be reviewed by a hearing officer jointly appointed by the NFL and the NFL Players Association.

Branch will miss Detroit’s upcoming Monday night game against the Tampa Bay Buccaneers and will be eligible to rejoin the active roster the following day.

The incident

The altercation occurred after Kansas City’s 30–17 win over Detroit on Sunday night. As players met near midfield, Chiefs quarterback Patrick Mahomes extended a hand for a high-five toward Branch, who walked past him. Smith-Schuster took offense and approached Branch, exchanging words before Branch struck him in the facemask, knocking him to the ground.

Smith-Schuster immediately jumped up and went after Branch. Chiefs running back Isiah Pacheco attempted to separate the two, but tensions escalated when Branch ripped off Smith-Schuster’s helmet as players from both teams rushed in.

Coaches and teammates eventually broke up the scuffle, and both sides left the field shortly afterward.

Following the game, Branch acknowledged his mistake:

“It was a childish thing, but I’m tired of people doing stuff between plays and the refs don’t catch it,” he said. “They try to bully me out there. I should’ve never done it — it was childish.”

This isn’t Branch’s first disciplinary issue this season. Last month, he was fined $23,186 for facemask and unsportsmanlike conduct penalties against the Green Bay Packers.

Branch’s intention to appeal the latest suspension was first reported by NFL Network.