Vikings co-defensive coordinator Adam Zimmer said Tuesday he's not sure whether linebacker Anthony Barr will be available in less than three weeks when the team opens the regular season on Sept. 12 in Cincinnati.

Barr, one of head coach Mike Zimmer's key defenders, has not practiced in two weeks as absences that were initially called rest-related by coaches have been revealed to be related to an undisclosed injury.

Injured players are typically seen rehabbing on a side field or in the weight room, but Barr has not been spotted doing any physical work in front of reporters over the past two weeks.

"I can't tell you if he's going to be ready Week 1 or not," Adam Zimmer said Tuesday. "He's doing everything he can rehab-wise to get back in there. Hopefully, we have him Week 1. If not, we'll have somebody step in and play."

Barr, a 2014 first-round pick, has previously played through hand, back and groin injuries while starting 87 regular-season games for the Vikings. Last year, he underwent season-ending surgery to repair a torn pectoral muscle in September. He also had season-ending knee surgery to repair a meniscus tear in December 2014.

When approached by a reporter after practice last week, Barr would only say he's "got some things I've got to take care of" when asked about why he's missing practice. Mike Zimmer added Saturday that Barr's health is a concern and they're being cautious.

Barr agreed to a restructured contract this spring, which reduced his pay this season but also allows him to become a free agent in 2022. The Vikings defense might still be without Barr to start the season, in which case one of their young linebackers would need to step up.

"We'll work through that," Zimmer said. "Whether it be playing a different package or one of the guys we have on the roster. Troy [Dye] has played multiple positions for us before. Chazz [Surratt] can play multiple positions, and I thought Blake [Lynch] did a nice job the other night."

'Rush like Everson'

Co-defensive coordinator Andre Patterson pumped the brakes on expectations for defensive end Everson Griffen, but it's clear the Vikings have plans if the 33-year-old pass rusher proves he's in the condition to contribute. Patterson reiterated that Griffen will be a situational pass rusher, evident by his third-down reps with the starting defense in Tuesday's practice.

That role will fit him best at this stage of his career, Patterson said.

"He gets to hit the field when there's a pretty good percentage they're going to throw the ball," Patterson said. "That helps him. I think the other thing that helps him when you get to be his age, is not having to play 60-65 plays a game."

Patterson likened Griffen, who started 87 regular season games for Patterson from 2014-2019, to a Picasso painting that was mimicked poorly by the Cowboys and Lions last season. Griffen still had six sacks for those defenses, but Patterson said the Vikings can deploy him differently to potentially be more disruptive.

"I'm just going to try to get him to rush like Everson," Patterson said. "He knows what that is, and I know what that is, and that's something we came up with in the seven years together that was the best style for him."

Osborn earning trust

As injuries limit the workloads of receivers Justin Jefferson (shoulder) and Adam Thielen (quad) during practices, second-year receiver K.J. Osborn has put in productive work at multiple receiver positions — split end, slot and flanker — to build trust with the coaching staff.

Offensive coordinator Klint Kubiak's first play call during Tuesday's practice scrimmage was a reverse to Osborn that netted about 10 yards.

"We've got a lot of trust in him," Kubiak said. "He can play multiple positions and he's a very intelligent player. He's smart and the details matter to him. With a player at wide receiver, they have to because you have to play so many spots. So, I'm pleased with his work habits."

Growing on the job

Rookie receiver Ihmir Smith-Marsette's 41-yard kickoff return against the Colts wasn't supposed to happen. The fifth-round pick took the ball out of the end zone despite being farther than 5 yards back, which is too far for coaches to give him the green light.

Smith-Marsette's elusiveness and speed on the return show his potential, but the decision showed his room for improvement in situational awareness, according to special teams coach Ryan Ficken.

"He needs to understand. To be a returner, you just don't take everything out," Ficken said. "We've got to understand the situation of the game, where we're at on the field and how that kind of works. That's part of him growing as a returner, and that's what we're going to continue to build on."

Seven sidelined at practice

In addition to Barr being held out, tackle Christian Darrisaw (groin), Thielen (quad), tight end Tyler Conklin (hamstring), running back Alexander Mattison (undisclosed), guard Dru Samia (undisclosed), and running back Kene Nwangwu (knee) did not practice Tuesday.

Defensive tackle Sheldon Richardson returned after missing Monday's session. Defensive tackle James Lynch continued to ramp up his work, taking 11-on-11 reps, after injuring his ankle in the Aug. 14 preseason opener.

Safety Xavier Woods remains limited with an undisclosed injury. Rookie safety Camryn Bynum continued to take first-team reps next to Harrison Smith.