DETROIT >> This one was intense, even before the game.

Green Bay Packers coach Matt LaFleur had a lengthy and heated exchange with a Lions fan before Thursday night’s game at Ford Field, and LaFleur had to be separated from the fan by Packers assistants and even a player.

The Lions fan was on the field as one of the American flag holders for the playing of the national anthem.

After the game, a 34-31 Lions victory, LaFleur explained what happened this way:

“I’ve never been a part of something like that. He was talking junk to our players, giving them the throat-slash sign and, you know, you’re trying to de-escalate it, and then he gets in my face. I thought it was pretty unsportsmanlike … I’ve never seen that. I’ve been on many fields, and usually, they police that much better.

“I thought it was an arrogant fan that, you know, wanted to get in part of the action. I would like to see security or something step in there and get him out of there.”

The house lights were off during the interaction between the fan and LaFleur, but it was caught by the TV cameras and NFL Network later played the clip — which began with LaFleur walking briskly onto the field and screaming and gesturing at the unidentified fan, who was wearing a blue Lions Brian Branch jersey.

The fan then got in LaFleur’s face, as fellow fans — there were dozens of them on the field during pregame, as holders of the massive American flag — began to capture the encounter on their cell phones.

Two Packers assistant coaches and Packers receiver Jayden Reed, the former Michigan State star, got between LaFleur and the fan and calmly escorted the coach toward Green Bay’s sideline. That wasn’t enough for LaFleur, who turned back around, ripped off his headset and started gesturing toward the fan again, before he had had enough.

“He shouldn’t be doing that,” LaFleur said of the fan.

LaFleur, 45, is a Mt. Pleasant native and an alum of Western Michigan and Saginaw Valley State. Earlier in his career, he coached at Saginaw Valley State, Central Michigan and Northern Michigan.

With the win, the Lions improved to 12-1, clinched a playoff spot and remained the front-runner for the No. 1 seed in the NFC. The Packers fell to 9-4, as the Lions swept the season series, including the 24-14 win at Green Bay on Nov. 3.