GREEN BAY – Just a few weeks ago, it appeared this Monday night clash between the Packers and Lions would determine the front-runner in the NFC North heading into the second half of the season.

The Vikings had lost their star rookie running back, Dalvin Cook, for the season and were dealing with an injury to quarterback Sam Bradford to boot.

The Lions had jumped out to a 3-1 start that included a victory over Minnesota, with their lone loss an inches-away defeat against defending NFC champ Atlanta.

The Packers were 4-1 after a last-second comeback victory in Dallas heading into a stretch of three division games out of four.

But so much has changed, of course. While Minnesota has weathered its injury issues to get to 6-2 at its bye, Detroit has dropped three straight and Green Bay is on a two-game slide following the injury to two-time MVP QB Aaron Rodgers.

Which makes Monday night’s game just as important, but for different reasons than expected. The Packers (4-3) don’t want to fall two games behind the Vikings at the midway point, especially not after having already lost to them. The Lions (3-4) certainly dread the prospect of dropping three games off the division lead.

At moments like these, teams turn inward. As division rivals, the Packers and Lions know each other so well that preparation isn’t as much about the opponent as it is about oneself.

That’s the mode both Green Bay and Detroit found themselves in this week.

Coming off their bye week, the Packers got introspective with an “across the hall” project, whereby offensive players and coaches met with their defensive counterparts to get an internal scouting report. To oversimplify the exercise, it’s about one side describing how it would go about planning to defeat the other.

Offensive linemen met with defensive linemen and pass rushers. Receivers met with defensive backs. Linebackers met with running backs. What do you see in my game? How would you beat me?

“It’s about having an opportunity to break it all down,” Head Coach Mike McCarthy said. “You talk about techniques and fundamentals, things you have time for in the training camp environment.

“I felt it was beneficial to do coming off the bye week. We’ve done it for a number of seasons now. It’s an opportunity to educate, talk football, and detail the most important things.”

The players not only appreciated the change of pace to one day’s pre-practice routine, but they liked the insight, too.

“We get to go work with the running backs, and it’s good for us to see what their mindset is,” inside linebacker Blake Martinez said. “As a linebacker, you want to play like a running back when you’re back there. You want to see and read things like he would, hit a hole like he would. On a given type of play, run or pass play, (we ask) what is your thought process when you’re looking at a linebacker? It’s helped me a lot.”

Internalization seemed to be the story of the week in Detroit, too. Listening to head coach Jim Caldwell’s conference call, he gave nothing but wordy praise for everyone in a Green Bay uniform, but in talking about his own team, the answers were simple: “We just have to play better.” “We’re not where we want to be.”

In other words, the Lions are focused on themselves, and it makes sense. They’ll have to react and adjust to some unknown Monday night anyway, seeing how QB Brett Hundley operates in McCarthy’s offensive system. They can’t prepare for everything in advance.

They’re also coming off a game against a high-quality opponent in which they did plenty of things right.

Detroit’s defense generated two turnovers and held Pittsburgh’s Le’Veon Bell to just 76 rushing yards. The offense produced a whopping 482 yards, with quarterback Matthew Stafford throwing for 423, yet scoring drives bogged down. They kicked five field goals and had two fourth-and-goals stopped in the second half.

So, both teams had their reasons for a little soul-searching this week, and they’re both looking to get what began as promising seasons back on the right track.

The Packers need their first win with Hundley at the helm, and the Lions need their first win in over a month.

For both teams, this game is not about the other guys. It’s about themselves.