The Green Bay Packers quarterback was rolling out to his right with Barr pressuring him. As Rodgers threw, Barr hit him in the midsection, and Rodgers landed on his throwing shoulder.
Brett Hundley replaced Rodgers in the 23-10 loss. The third-year pro is the only other quarterback on the Packers' roster, but the team is expected to promote Joe Callahan from the practice squad.
"It's devastating, no question about it," Packers receiver Randall Cobb said in a somber visitors' locker room at U.S. Bank Stadium. "First and foremost, it's one of my closest friends, so to see him go down with that, it's tough. But we've still got to play football. We've got a long season ahead of us, and we've got to figure out what we're going to do."
Coach Mike McCarthy plans to do that with Hundley. He reiterated that twice during his postgame news conference.
"Brett Hundley's my quarterback. Joe Callahan's the backup," McCarthy said. "That's the direction we're going. That is the focus. And that's where we are as a football club."
Hundley's first pass of the day was intercepted by cornerback Xavier Rhodes, which led to a Vikings touchdown drive. Hundley threw two more interceptions, along with a touchdown, and finished 18-of-33 passing for 157 yards in his first meaningful regular-season action since the Packers picked him in the fifth round of the 2015 draft.
Rodgers missed seven starts in 2013 when he broke his left collarbone. This time he is expected to be out longer because it's his throwing shoulder. Rodgers did not have surgery four years ago. It has yet to be determined if he will need it now.
Barr hit Rodgers on a roll-out pass to his right and maintained contact with the quarterback all the way to the ground. Rodgers appeared to yell at Barr as he walked off the field with the Packers' medical staff.
"I saw Aaron jawing at him," Packers linebacker Clay Matthews said. "Aaron can take a hit and get up and respect it, but I'm sure he had a little something to say and rightfully so."
Hundley said he could understand why Rodgers wouldn't like the hit.
"I'm sure he didn't, yeah," Hundley said. "I mean, who would?"
Rodgers did not speak to reporters after the game. Barr was not available to reporters either because he left the game due to a concussion.
The Packers went 2-4-1 without Rodgers the last time he broke his collarbone and used three different quarterbacks: Seneca Wallace, Scott Tolzien and Matt Flynn. It was Flynn who kept Green Bay's playoff hopes alive by going 2-2 in four starts. Rodgers returned for the regular-season finale at Chicago, a game the Packers won to win the NFC North and make the playoffs.
"In my opinion, he's the best player in football, but this is a team game," McCarthy said. "This is the ultimate team game. And we need to be better. And we need to be better with the 11 people on the field that we have, regardless of the phase that we're in, and ultimately that's my responsibility."
Since 1992, the Packers have used the fewest starting quarterbacks (six) of any team.
If Hundley starts next Sunday against the Saints, it would be just the 13th game since 1992 in which a quarterback other than Rodgers or Brett Favre started for the Packers.
The Vikings' game was the first time all season that Rodgers had both of his starting tackles -- David Bakhtiari and Bryan Bulaga -- playing together. But this wasn't a protection issue. Rather, it was Rodgers on a rollout pass that tight end Martellus Bennett dropped. Rodgers was able to walk off the field under his own power. The Packers' medical staff examined Rodgers on the sideline, then took him to the locker room on a cart.
By game's end, the Packers had lost three of their five starting offensive linemen. Bakhtiari dropped out because of his recurring hamstring issue. Bulaga sustained a concussion, and guard Lane Taylor suffered injuries to his right ankle and knee.