The Redskins placed running back Derrius Guice on the injured reserved list Friday. (John McDonnell/The Washington Post)

The Washington Redskins placed running back Derrius Guice (knee) and defensive lineman Caleb Brantley (foot) on injured reserve Friday. Guice had surgery on the meniscus in his right knee this week after being injured in the season-opening loss in Philadelphia. Both are eligible to return after eight weeks and can start practicing after six. Teams can bring back just two players off IR during the season.

The Redskins also will be without defensive lineman Jonathan Allen (knee) and tight end Jordan Reed (concussion) in Sunday’s home opener against the Dallas Cowboys. Allen’s sprained MCL is not considered serious, and he could be back next week against the Chicago Bears.

Tim Settle is expected to start in place of Allen, while T.Y McGill and Treyvon Hester were recently added to provide depth. The team kept just five defensive linemen on the original 53-man roster.

“It’s a test,” Coach Jay Gruden said, “Hester has played some ball at Philadelphia. He came in in great shape. McGill also kind of got a little bit of familiarity of the system. He can do a little bit of different things, but it’s a matter of, if they’re out there, can they do the right things and be in the right spot? I think they can. Both smart guys, both physical guys, so that’s good.”

Reed suffered a concussion in the third preseason game and returned to practice last week, but he remained in the concussion protocol and missed the game in Philadelphia. He practiced Wednesday and Thursday but missed Friday’s practice before officially being ruled out.

“He’s a special guy; if he’s in the game, you have to design a few plays for him,” Gruden. “So, those plays just got red-penned. They just got axed. But at the end of the day, we still have a lot of good players, lot of good weapons that we can still attack a defense. We’re not worried about that. Main thing is worried about Jordan getting well, and hopefully that’ll be next week for Chicago.”

Cornerback Quinton Dunbar (knee) is listed as questionable, and cornerback Fabian Moreau (ankle) is doubtful. Dunbar did not practice Thursday or Friday and Moreau was limited in practice all week. Gruden said Dunbar’s knee swelled up after practice Wednesday, and veteran Dominique Rodgers-Cromartie probably will fill in if Dunbar can’t go.

“DRC is a vet,” Gruden said. “He’s seen every coverage, played every coverage, played a lot of great players in his day — man-to-man, zone. So he’s a veteran guy. It’s the reason why he’s here, really, just in case something like this were to happen. We feel pretty good that DRC can play and play at a pretty good level.”

Former Texans cornerback Aaron Colvin was signed Friday to help the banged-up secondary, the team announced. Colvin was released after having a rough outing during a 30-28 loss to the New Orleans Saints on “Monday Night Football” in the Texans’ opener. He was in the second year of a four-year, $34 million deal. The veteran does not have an interception since being selected by the Jaguars in the fourth round in 2014. His best season came in 2015, when he started 15 games and had 73 tackles, four sacks and seven passes defensed.

Wide receiver Robert Davis was also added to the 53-man roster from the practice squad, and cornerback Deion Harris was signed to the practice squad.

The Cowboys will be without wide receiver Tavon Austin (concussion) and linebacker Luke Gifford (ankle) after both were ruled out Friday.

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