MANKATO, Minn. -- Minnesota Vikings linebacker Anthony Barr is dealing with inflammation in his left knee and missed his second straight practice on Thursday afternoon. Vikings coach Mike Zimmer didn't sound concerned about Barr's injury lingering into the season, however.

"We're being careful with him," Zimmer said. "He's frustrated, but our plan is to continue to get him ready for Sept. 14," which is the regular-season opener in San Francisco.

Barr, who had surgery to repair a slight meniscus tear last season, missed most of the Vikings' offseason workouts with what Zimmer said was a different injury. He got off to a slow start in training camp, as the Vikings tried to get him back into football shape and had to pull back on practice earlier this week. He's been doing rehab work the last few days.

"It's legitimate -- it's not like it's not a legitimate concern," Zimmer said. "But we anticipate he'll be back here pretty quick."

Zimmer said he hadn't determined whether Barr would play in the Vikings' preseason opener on Sunday night against Pittsburgh in the Pro Football Hall of Fame game, but it seems unlikely the Vikings would rush Barr into action.

"He did a lot of good conditioning and got a lot of reps in practice (before the inflammation flared up)," Zimmer said. "That's the thing right now -- we've got to get the injury settled down and then start working on conditioning."