When you're two historic division rivals battling for a playoff spot, it's only natural for a brawl to break out.
That's what happened on Sunday between the Detroit Lions and Chicago Bears at Soldier Field.
Before the fight, Lions defensive tackle Nick Fairley had already drilled Bears quarterback Jay Cutler in the end zone, and Bears linebacker Lance Briggs had responded by taking a shot at star receiver Calvin Johnson in the air.
But after throwing his third interception of the game in the fourth quarter, Lions quarterback Matthew Stafford let out his frustrations on Bears cornerback D.J. Moore, basically trying to take his head off while Moore attempted to block him.
Moore responded by swinging around and rocking Stafford while he was on the ground and then chaos ensued, with both teams coming to their teammates' sides.
The Bears owned a 93-65-5 overall record against the Lions before hosting their bitter rivals on Sunday. But the Lions had rebounded this season behind Stafford and an improving defense and had beaten the Bears in Week 5.
So when the Lions found themselves down, 37-6, early in the fourth quarter, you could bet some of their emotions had already boiled over.
If the Bears win on Sunday, they improve their record to 6-3, while the Lions drop to 6-3. As the top two teams for a wild-card spot in the NFC coming into the contest, this was not only a divisional battle, it had playoff implications.
Welcome to the Bears-Lions rivalry, folks. It just got a whole lot more heated.