GREEN BAY—If there were a secret to it, it would have gotten out by now.

Packers Head Coach Mike McCarthy is asked every year what makes his team so successful in division games. Every year he gives roughly the same answer, that the coaching staff spends some extra time each offseason studying the NFC North opponents, knowing they constitute six of the 16 games on the schedule.

Beyond that, there doesn’t appear to be a magic formula.

“Every place I’ve ever coached at in the National Football League puts a big emphasis on division games,” McCarthy said.

Yeah, but McCarthy must have figured something out in what he referred to this week as a “heavyweight division.” Including two postseason wins following the 2010 and 2012 seasons, McCarthy is 37-12-1 against NFC North foes, an eye-popping winning percentage of .750.

That’s the track record McCarthy and the Packers take into as important an early-season stretch as any team could face. Beginning Sunday in Detroit, the Packers play all three of their division opponents in a span of 12 days, with a trip to Chicago next week and a Thursday home game against Minnesota right after that.

It’s a gauntlet that could determine whether the Packers, who have won the division title three years running, remain the team to beat in the NFC North, or if they’ll need to make up ground from behind, as they did last year following quarterback Aaron Rodgers’ broken collarbone.

“It’ll be tough. This is a stretch that could really have some implications on our postseason future,” Rodgers said. “Winning your division games is the easiest way to win your division, which guarantees you a home playoff game, so these are really important. Two of the three on the road, and then the third one is a short week. So, it doesn’t get easy, but that’s how we like it.”

The added wrinkle this year is that two of the three division opponents have new head coaches in the Lions’ Jim Caldwell and the Vikings’ Mike Zimmer. They’ll begin trying to do what no other NFC North head coach has been able to, and that’s get the best of McCarthy and the Packers over the long haul.

Caldwell has the most daunting history to overcome, as McCarthy went 6-0 vs. Rod Marinelli and 8-2 vs. Jim Schwartz. Zimmer’s predecessors – Brad Childress (3-7) and Leslie Frazier (1-5-1) – didn’t fare much better.

Marc Trestman took over in Chicago last year for Lovie Smith and went 1-1 in Rodgers’ injury and return-from-injury games. Smith won more against McCarthy than any division coach but was still just 5-10, with only two wins after a 3-1 start through McCarthy’s first two years (2006-07).

McCarthy’s success within the division is no fluke. He established the trend right away by going 5-1 in his first season, despite the team’s 8-8 overall mark. Two years later, when the Packers’ 6-10 record was their worst under McCarthy, they still went 4-2 in the division.

The players aren’t taking anything for granted, of course. Their most recent division game, which required a last-minute 48-yard TD pass on fourth-and-8 to prevail in Chicago, is freshest in their minds. That was McCarthy’s 19th division win by a single-digit scoring margin, just over half his total of 37.

“It’s going to be a grind,” receiver Jordy Nelson said. “Every division game is, especially on the road.”

That’s where the current stretch begins, and by the end of the second night in October, half of the Packers’ division slate for 2014 will be complete. That could be good or bad.

It’s no surprise the Packers and McCarthy have thrived in the past when faced with three straight division games, going 3-0 in both 2006 and 2012. The 12-day time frame, with two new head-coaching opponents, just adds to the challenge this time.

“We’re not looking too far ahead,” linebacker Clay Matthews said. “We take this a game at a time, and Detroit is first up.”

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