Washington was a much better running team in the five games that Kory Lichtensteiger (78) started at center than in the 11 since. The offensive lineman will be back for the playoff game. (John McDonnell/The Washington Post)

The Washington Redskins learned Monday that rookie defensive back Kyshoen Jarrett — one of the most versatile members of their secondary — will miss Sunday’s first-round playoff game against the Green Bay Packers after a head-on collision knocked him out of the regular season finale at Dallas.

Jarrett — a sixth-round pick out of Virginia Tech who blossomed into one of the surprises of this year’s Redskins draft class, contributing at nickelback, strong safety, free safety and on special teams — initially underwent testing for a concussion after a first-quarter tackle attempt that left him lying on the turf for several minutes. Doctors eventually ruled out a concussion but sent Jarrett for an MRI exam on his neck.

Coach Jay Gruden said Monday afternoon that Jarrett’s neck had no structural damage. However, the collision left Jarrett with nerve damage that has reduced strength and range of motion in his right shoulder. As a result, he will not play this week and his season could be over.

The 5-foot-10, 200-pound Jarrett played in all 16 games this season, starting six of them and recording 58 tackles, four pass breakups and a forced fumble.

“Obviously, the loss of Kyshoen is very important because he played safety, nickel and did a little bit of everything — special teams. That’ll hurt us,” Gruden said. “It has an effect, it really does, because he’s so versatile. [Defensive coordinator Joe] Barry and [Defensive backs coach Perry] Fewell are out there right now coming up with a plan of who is going to play where and how.”

The Washington Post's Gene Wang and Scott Allen discuss the Redskins' Week 17 win over the Dallas Cowboys. (Thomas Johnson/The Washington Post)

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Backup cornerback and special teams contributor Dashaun Phillips was carted off during Sunday’s game with a neck injury, but 24 hours later he had improved significantly and Gruden said it’s possible he could play this coming week.

Despite the loss of Jarrett, the Redskins enter the postseason with optimism because they’re healthy at several important positions. Clinching the NFC East championship in Week 16 afforded the team the opportunity to rest a number of banged-up veterans.

Starting free safety Dashon Goldson didn’t play on Sunday because of a fractured rib and shoulder injury. Goldson played with the rib injury in Week 16 and has dealt with the shoulder injury for weeks. Pro Bowl left tackle Trent Williams sat out Sunday’s game with foot and knee injuries. Running back Matt Jones sat with a hip pointer. Defensive end Jason Hatcher didn’t play because of a pinched nerve in his neck and knee inflammation, and although he dressed, wide receiver DeSean Jackson didn’t play a snap against the Cowboys.

Not playing has bought those players more time, and Gruden expects they will be effective in the team’s first playoff game in three years.

“I think getting Trent back will be huge, obviously, and Dashon at full strength,” Gruden said. “I think some of these guys were able to rest, getting them off a week going into the playoffs will be very, very beneficial to us. . . . Overall, I think the health of our football team is pretty good this stage of the year.”

Washington will also welcome back one more valuable piece to the puzzle this week. Starting center Kory Lichtensteiger has missed the past 11 games with a pinched nerve in his neck. Lichtensteiger spent eight weeks on the short-term injured reserve list while receiving treatment and working to regain strength in his left shoulder. He was permitted to practice the past two weeks. Lichtensteiger received a good deal of action last week while serving as scout-team center. Lichtensteiger and his coaches have expressed encouragement about his play.

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Asked about Lichtensteiger on Monday, Gruden said: “Kory’s back and he’s able to be activated from his injured reserve, which is a good thing. He feels really, really good.”

Lichtensteiger will serve as a much-welcomed presence on a line that has remained solid in pass protection during his absence but has struggled blocking on run plays. In the five games Lichtensteiger played, Washington averaged 121.8 rushing yards. Without him, the Redskins have managed just 87 rushing yards per game.

Josh LeRibeus has made 11 starts filling in for Lichtensteiger, but he’s struggled getting to the second level on run blocks and being consistent with his shotgun snaps. LeRibeus’s snaps have sailed high and errant, and at times he has forgotten snap counts, causing Washington to draw false start penalties.

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The Redskins have no margin for error as they host the Packers, who have reached the playoffs in each of the past seven years. Green Bay lost its final two regular season games — including Sunday night’s NFC North-deciding game against Minnesota. However, at 10-6, the Packers remain a talented team.

“Green Bay obviously with Aaron Rodgers at the trigger is a very good football team,” Gruden said. “Coach [Mike] McCarthy has won a lot of football games and a lot of big football games. . . . A very good team that has had a very couple of rough games as of late, but they’ve had the ability to turn it up come playoff time. They have the experience, and that’s something we’re going to have to deal with.”