Derrius Guice's knee injury means Redskins Coach Jay Gruden will turn back to the player he didn't even dress on Sunday: Adrian Peterson. (John McDonnell/The Washington Post)

The news wasn’t a surprise, but given what has happened the past few days, it seemed monumental. With Washington Redskins running back Derrius Guice injured and seemingly unable to play Sunday against Dallas, Coach Jay Gruden said Adrian Peterson will start in Guice’s place.

A week ago the announcement would have seemed obvious. But that was before Gruden didn’t dress Peterson in Sunday’s season opener against the Philadelphia Eagles and punctuated the move by saying he would play Peterson when Guice is also available only if “we think we can run the ball 55 times in a game in I-formation.”

Now that Guice has a meniscus injury in his right knee that will keep him out from anywhere between a week and a month, Gruden softened his tone about Peterson on Wednesday.

“No,” Gruden said when asked whether he and Peterson needed to talk about what happened over the weekend. “We’ve talked. He’s in a good place. Nobody’s ever happy if you’re the backup or not dressing, but you are still on the team and when your number is called, you roll. And Adrian is a pro, and I feel very good if his number is called this week, he will be ready to go and play very hard and he’ll be Adrian Peterson.”

Peterson ran for 1,042 yards last season, but he isn’t as well suited for Gruden’s offense as Guice. And the development seems to be frustrating Gruden, who is already hampered by the uncertainty surrounding tight end Jordan Reed, who suffered a concussion in the third preseason game and has yet to be cleared for games, even though he has been able to take part in a portion of the team’s practices the past several days.

The Redskins hope to get a definitive word on Reed’s availability Thursday, but the uncertainty of not having both Guice and Reed seems to leave Gruden more uneasy, especially with a talented Dallas Cowboys team coming to town for Washington’s home opener.

When asked whether the uncertainty surrounding Reed hampers his game-planning, Gruden agreed.

“It does a lot. He’s one of the better receiving tight ends in the league, so we are able to move him around a lot and do some different things with him,” Gruden said. “It’s just hard right now at this stage when you don’t know if he’s coming in or not, because there are plays that you design for Jordan you wouldn’t design for somebody else. No offense to that somebody else, [but] he’s different.”

Neither Peterson nor Reed spoke to reporters Wednesday. Guice wasn’t at Wednesday’s practice or around the locker room afterward. Gruden said Guice was having another examination on his injured right knee and held out a slight hope that the second-year running back could play Sunday.

Gruden also expressed hope that defensive lineman Jonathan Allen might be able to play against Dallas. Allen sprained his knee in the Philadelphia game. Gruden said Allen, who already had two MRI exams this week, was being examined Wednesday. Even if Allen isn’t able to play Sunday, Gruden said he felt confident he’d be cleared for the team’s next game, Sept. 23 at home against Chicago.

Another injury that could be a problem is a foot injury suffered by safety Montae Nicholson, who missed practice Wednesday. Gruden said he is hopeful Nicholson will be able to play against the Cowboys. Less certain is the status of backup defensive lineman Caleb Brantley, who has been battling a foot problem for several weeks and had to leave Sunday’s game. He missed practice Wednesday, too.

Cornerbacks Quinton Dunbar and Fabian Moreau both were limited in Wednesday’s practice. Dunbar is dealing with a sore knee and Moreau missed the opening game with a sprained ankle.

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