EDEN PRAIRIE, Minn. (AP) — Stevan Ridley was at home in Mississippi, spending time with family and preparing for hunting season, when the Minnesota Vikings invited him this week to work out for their unexpected opening at running back.

Rookie star Dalvin Cook went down with a torn ACL in his left knee , an injury that Ridley knows all too well.

It's also the type of adverse and sudden development that Ridley was resigned to watching for around the league, as a free agent without a team.

"I was just down there really trying to hold on and stay in shape to the best of my abilities," Ridley said, "and just hoping that that call came through and the door would swing open somewhere."

The opening came on Sunday, when Cook tried to cut to dodge a Detroit defender and dash further up the field . He fumbled the ball and crumpled to the turf, his first NFL season reduced to just a tease with 444 total yards and two touchdowns in four games.

The Vikings have experience and skill-set variety with Latavius Murray and Jerick McKinnon, but they'll likely need more than those two to help share the load in Cook's absence. They worked out Ridley on Wednesday and signed him on Thursday, when they placed Cook on injured reserve.

"I've got a lot to learn in a little bit of time," Ridley said. "Get in here and try to find a role with the team and help these guys contribute."

Ridley was a third-round draft pick by New England out of LSU in 2011. He has 2,914 yards on 688 carries for three teams, for an average of 4.2 yards per attempt. He rushed for 1,263 yards and 12 touchdowns for the Patriots in 2012.

Then came the fateful game on Oct. 12, 2014, four weeks after he rushed for 101 yards and a touchdown on 25 carries against coach Mike Zimmer and the Vikings, when his right knee buckled, resulting in ACL and MCL tears.

He joined the New York Jets in 2015 and appeared in one game with the Atlanta Falcons last season. Ridley was in training camp with Denver this year, but the Broncos released him during the final cuts before the regular season.

So here he is at age 28, past the prime years at this wearing position, hoping to catch on and carve out a late-career niche with another new team.

"It's been tough, man. It's been a lot of ups and downs, a lot of different stops. A lot of hoping and praying that things work out," Ridley said .

"You never really know what's going to be the last play or when's going to be the next play. So this call came unexpected and the stop before this was kind of unexpected, so being in the NFL you really never know."

Ridley, who also tore his ACL once in college, ought to at least be able to provide some advice and encouragement for Cook as he gets to know his new teammate in between cram sessions with offensive coordinator Pat Shurmur's playbook.

"It's a challenge going forward, and you have to really just prepare yourself and know that there's going to be days that it's terrible, but you can get through it, you can push through it," Ridley said.

How about now, almost three years later?

"Honestly, I really don't even feel it. A lot of times I refer to it as my bad knee, but truly it's really your stronger leg," Ridley said. "If you really follow the process or you rehab the way you're supposed to, you don't really notice it."

For now, Ridley will try to catch up while Murray carries the load and McKinnon adds his unique skills to the mix. Murray has seen only limited action to date, because of ankle surgery in March.

"It's always good when you have a Pro Bowler coming in. He's really starting to come into his own," tight end Kyle Rudolph said. "Obviously he missed a lot this offseason with the injury, but he's had time to get comfortable, and he's ready to roll."

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