The last time the Patriots and the Bills met, back in Week 4, there was a pregame scuffle that began when a Bills player pushed New England rookie quarterback Jacoby Brissett.

It might all seem unprovoked but the Bills took issue with several Patriots players -- including Brissett -- running through their warm-up area. The Bills went on to win that day, 16-0. And now, four weeks later, the teams face off again.

On Thursday, coach Rex Ryan suggested that in the first matchup, Brissett broke an unwritten rule and that exacerbated everything that followed.

"It's no big deal. It's kind of an unwritten thing in the NFL," Ryan said, via ESPN.com's Mike Rodak. "So whatever happens, it's no big deal. Focus is on just playing the game."

So what, exactly, is that unwritten rule?

"I mean, you got your spot on the field where you're supposed to be, and that's just the way it is. It's always been that way for the 20 years I've been in the league and much longer than that," Ryan explained. "But trust me, it's no big deal. I've never thought one second of it. It's about the game, and that's all that matters."

It may not be a big deal to Ryan, but his players feel differently.

"It's gonna be the same reaction that they got last time," Bills defensive back Nickell Robey-Coleman said Wednesday. "There ain't no other way around that situation, you know? Just respect each other's sideline and move on."

Cornerback Stephon Gilmore added: "We're not gonna let nobody push us around. You know what I'm saying? We're gonna play smart. We know them guys like to try to get under your skin and make you react a certain way. We're gonna try to take it in between the lines and play good football."

Meanwhile, shortly after the original incident, Patriots president Jonathan Kraft ripped Ryan for what happened.

"I think if you are less-than-disciplined in your personal approach, your team takes on the attitude of the coach," Kraft said, according to CSNNE.com's Phil Perry. "... My guess is Rex probably loves that. That's why Rex is Rex. And that's why Bill [Belichick] is Bill."

Unlike the last meeting, Tom Brady will be under center for the Patriots. In related news: All eight CBSSports.com experts are not only picking the Pats to win, they expect them to cover the six-point spread.