The Vikings, in theory, will face a familiar foe at Soldier Field on Sunday.

When they fired up the film on the Chicago Bears this week, they saw the same classic navy, white and orange uniforms. They recognized Jay Cutler, Chicago’s strong-armed, slumped-shoulder quarterback. And they spotted Matt Forte and Alshon Jeffery, two playmakers who have given them problems in the past.

But so much has changed for the Bears since the Vikings last saw them face-to-face.

The Bears during the past 10 months have hired a new general manager, changed coaches and remade their roster, especially on defense.

“We’re battling, and there are a lot of changes,” said new Bears coach John Fox, who previously oversaw overhauls in Carolina and Denver. “You’ve got players learning new systems in all three phases, players getting used to the coaches, coaches getting used to the players.”

The Bears let outside linebacker Lance Briggs and cornerback Charles Tillman, Pro Bowl performers and longtime defensive leaders, walk in free agency. They cut veteran center Robert Garza, who snapped in their last Super Bowl appearance in 2006. They traded talented but outspoken wide receiver Brandon Marshall.

They brought in 13 unrestricted free agents, including pass rusher Pernell McPhee, slot receiver Eddie Royal and starting safety Antrel Rolle. Cornerback Tracy Porter, another starter, was signed after getting cut by the Washington Redskins.

The changes didn’t end when the season started. After the Bears started 0-3, they traded former Vikings defensive end Jared Allen, a misfit in their new 3-4 defensive scheme, for a draft pick. They also dealt linebacker Jonathan Bostic and cut safety Brock Vereen, another former starter. Vereen is now on the Vikings’ practice squad.

Defensive tackle Jay Ratliff was cut last week and security had to escort him out of the team facility after an altercation with new General Manager Ryan Pace.

“It’s just culturally what kind of players you want, what kind of competitors they are, you know, the culture of your building,” Fox said of all the changes.

Despite the turnover, the Bears have at least become competitive, winning a pair of games before losing an overtime shootout to the Detroit Lions before their bye week.

The Bears have been balanced under new offensive coordinator Adam Gase, whom Fox brought with him from Denver. They continue to keep Forte, one of the league’s best all-around running backs, busy. And they have reined in Cutler to some degree.

While the turnover-prone quarterback has coughed up the ball once in each of his five starts, he led game-winning drives against the Oakland Raiders and Kansas City Chiefs and put the Bears into position for a field goal that sent the Lions game to overtime.

“Like anybody adjusting to a new system, there are growing pains,” Fox said of Cutler. “But as far as attitude and mentality, he’s done every single thing from the minute we got here, from learning the offense, understanding that there’s a lot to it. I think he just gets better and better every week.”

The return of Jeffery, his big-play receiver, from a four-week absence provided a boost against the Lions. Jeffery had eight catches for 147 yards and a touchdown.

Defensively, Fox and the Bears brought in coordinator Vic Fangio from San Francisco and have several new starters, including McPhee, who came from Baltimore, and second-round nose tackle Eddie Goldman.

Under Fangio, the Bears utilize a 3-4 front in their base defense and use a bunch of different coverages, unlike the Bears of old with Briggs, Tillman and Brian Urlacher.

“It’s very weird preparing for them and not seeing a lot of Cover Two because that’s what they used to do,” wide receiver Jarius Wright said.

The transition is far from complete, though. Holes remain at a few key spots and the Bears are ranked last in the league in scoring defense.

“They’re playing good,” said coach Mike Zimmer, who changed up the Vikings defense when he was hired in 2014. “They’re physical.”

Despite an offseason spent playing getting-to-know-you in Chicago, the Bears seem likely to experience more major changes after this season. Jeffery and Forte will both be free agents and Cutler could also be a goner if he doesn’t win over Fox and the coaches.

But in the short term, the Bears on Sunday hope to look like the same old Bears to the Vikings, who have not won at Soldier Field since 2007.