MINNEAPOLIS -- The Minnesota Vikings placed safety Michael Griffin on injured reserve Saturday afternoon, ending the two-time Pro Bowler's bid to start next to Harrison Smith.
Griffin, who was on crutches in the team's locker room Sunday after his back seized up against the San Diego Chargers, did not play in the team's final preseason game against the Los Angeles Rams on Thursday night.
On Saturday afternoon, he posted a message on Instagram that suggested he'd been released: "Just want to thank the @vikings organization for the opportunity and want to wish them the best this season. Thanks for memories and friendships that will never be broken. #skolvikes"
The safety said he wasn't sure at the time if the Vikings would release him or put him on injured reserve, but when he was playing on a one-year deal at age 31, he figured the net effect of the move was the same.
"It was more likely I wasn't going to be able to play next week," Griffin said. "I felt like the writing was on the wall. You're not going to keep a guy who's going to be injured, and you don't know how long he was going to be out. I got an epidural shot on Monday; it's getting better, but I don't know when I'll be able to be fully 100 [percent]."
Griffin said he plans to get a second opinion on his back, which he first injured several days before the Vikings-Chargers game. "We didn't know exactly what it was. I thought I could play, but a couple plays into the game, it just locked up," he said. "I was trying to make the team. When you're an older guy, and you're not playing, it's not going to help."
Griffin had man-to-man coverage on a Chargers' tight end when Melvin Gordon broke through the line, forcing Griffin to make a quick change of direction in pursuit of the running back. Gordon sprinted away for a 39-yard touchdown, which was the first in U.S. Bank Stadium history.
The Vikings signed Griffin to a one-year, $2.5 million deal in March, hoping he could turn into the kind of dynamic safety they've sought next to Smith. Griffin, though, lost out on the starting job to Andrew Sendejo while fighting through his back injury.
Minnesota will keep seventh-round pick Jayron Kearse after an impressive preseason in which the Clemson product intercepted two passes and forced a fumble. Anthony Harris, who started two games in 2015 after the Vikings signed the safety as an undrafted free agent, also made the Vikings' final roster.