GREEN BAY – The preseason finale barely over, Kevin King already was grinning from ear to ear with anticipation for the Packers' regular-season opener against Chicago.

"We're ready to have fun," said King afterward in the visiting locker room at Arrowhead Stadium. "That's the one thing we all talk about. Man, we're going to have so much fun this year. Try to bring that new swag to the defense."

On Sunday, eight months of research and development under new coordinator Mike Pettine will be put to work when Green Bay unveils its new defense against its biggest rival.

Linebacker Clay Matthews joked Thursday the Packers probably showed "5 percent" of their scheme during an otherwise vanilla preseason. Other than a few creative pass-rushing sets in third-down situations, precious little has been revealed about Pettine's plans.

Behind closed doors and in practice, however, the Packers believe they established a blueprint this offseason to return the defense to prominence.

Pettine has had a Midas touch for turnarounds in his previous coordinator stints with the New York Jets (2009-12) and Buffalo Bills (2013), overseeing top 10 defenses in five consecutive seasons.

As much as this offseason was about getting 11 guys to play as one on the field, Pettine also has stressed the importance of attitude with his players this summer.

"I think we're trying to set an identity as opposed to showing up and hoping for the best," Matthews said. "I think it started with an attitude and mantra when we first came in here. That's just to be flying around, physical, getting after the quarterback, taking the ball away, like the other 31 defenses in the league.

"But, you know, I think the guys have really bought into it. Mike definitely has an ability to call games, understand concepts from offensive coordinators and put us in the best position possible."

Pettine has been upfront from the start in saying he can't guarantee sacks or takeaways, but his "likeable and learnable" mentality to coaching defense quickly won over players.

During organized team activities, Pettine met individually with every player on defense and had them write down goals for the season. He also delivered a roaring speech to the team at the start of training camp that quarterback Aaron Rodgers later called “an all-timer.”

Pettine's base philosophy is he wants to be "more calculated than reckless" when it comes to blitzing, with simple terminology, strong communication and unpredictable pressure being the hallmarks of the scheme.

Pettine looks to generate pressure across the line and prides himself on not allowing the opposing quarterback to diagnose safeties, linebackers and would-be blitzers.

"We want to try to affect all quarterbacks," Pettine said. "That's a big part of being successful on defense in the league. I don't think we necessarily get caught up in what they're doing and what they're capable of, but (it's about) our core philosophy in all phases.

"Whether it's disguising coverage, mixing coverages, whether it's pressure, what's it's just the pass rush, we need to affect the quarterback. If we're not sacking him, we're flushing him out and forcing him to throw it away or we're knocking him down."

Behind that front is a secondary featuring an encouraging blend of experience and potential with returning former Pro Bowler Tramon Williams, All-Pro safety Ha Ha Clinton-Dix and eighth-year veteran Davon House leading a young group.

This summer, the Packers invested their first two draft picks in their defensive backfield with the selections of Louisville's Jaire Alexander and Iowa's Josh Jackson, who each had an interception during the preseason.

Factoring in King, Kentrell Brice and several other young defensive backs, the unit reminds Clinton-Dix of 2014 when Green Bay ranked inside the top 10 in pass defense and made a deep playoff run with help from an array of defensive backs, including the former first-round pick out of Alabama.

"We have a lot of depth in that room," Clinton-Dix said. "It feels like how it was when I was a rookie in the league. I didn't know the talent that we had in the room, from corner to safety, but now that I'm a little older and a lot of experience, I think we've got a chance to be special."

Although Head Coach Mike McCarthy acknowledged the "honeymoon ends" for all 32 NFL teams starting this weekend, there's optimism about what Pettine has been selling on defense.

The defense knows it must now prove it on the field. After talking all offseason about the new direction, the Packers are eager to show what's been behind the curtain.

"Everybody is excited for it to be the real thing," King said. "We play the preseason and stuff, but that's kind of just getting your feet wet. You get in a few plays here and a few plays there, but actually getting out there and playing a whole game, get the juices flowing. We're just going out there and letting it all loose."