ASHBURN, Va. -- Redskins running back Derrius Guice suffered an injury to his right knee Sunday and could miss some time, according to coach Jay Gruden, potentially paving the way for Adrian Peterson to get more playing time in Washington's crowded backfield.

Gruden said Guice felt soreness in his knee after the game and was undergoing an MRI on Monday afternoon. Gruden is not yet ready to rule out Guice for Sunday's game against Dallas.

A source told ESPN's Jeremy Fowler that Guice has a meniscus injury and that he hopes to be fully recovered within a few weeks. Sources told ESPN earlier Monday that Washington was uncertain whether Guice would miss any games.

Even if Guice can play, Gruden said there's a chance the Redskins would keep Peterson active, especially if they have concerns about Guice's durability. Peterson was declared a healthy inactive for the first time in his career before Sunday's 32-27 loss to Philadelphia.

"The whole point of having one lead down back is making sure that guy can handle the carries. If he can't handle all the carries, then you've got to have two," Gruden said. "Fortunately, we have AP in the building."

Gruden said "for sure" that Peterson would be active if Guice can't play. Guice missed all of last season with a torn left ACL. He also suffered a hyperextended left knee while at LSU.

Guice carried 10 times for 18 yards against the Eagles.

Peterson was inactive Sunday in large part because of special teams needs. The Redskins typically keep only three running backs active, and they knew almost the entire offensive workload would be handled by Guice and Chris Thompson. Washington kept Wendell Smallwood active because he plays special teams.

"Adrian is well-liked in the locker room. He's well-liked by the coaches. He's well-liked by everybody," Gruden said. "It wasn't an easy decision to make him inactive, without a doubt.

"Obviously it's an issue. He's a great player. He had 1,000 yards for us last year. We have 15 games left. I expect Adrian Peterson to play and play well when he does. It could be this week. He's got a great attitude about it. I know he's not happy about it, but when his number is called, he'll be ready."

The Peterson move continued to resonate with his teammates, though it's debatable to what degree. Tackle Morgan Moses, during his paid weekly appearance on 106.7 The Fan on Monday, said, "Any time you've got a Hall of Fame guy that doesn't dress, man, it's a slap in the face.

"And obviously, we've gotta figure out what the reason is. And it's my job as one of the older guys on the offensive line to speak up and say, 'Hey, we need him.' Obviously, you don't put a Hall of Fame guy like that on the sideline. When he's healthy, as well."

Moses said after Sunday's loss that Peterson still has "a lot of juice left." He reiterated that during his radio spot.

"To have that guy just standing on the sideline is just ... it doesn't sit well to guys on the team or the NFL," Moses said. "So I think that's something we need to correct, man, because he's a hell of a football player."

Thompson, however, said while the news surprised players -- and that it was weird to see Peterson on the sideline in street clothes -- he didn't think it would linger.

"I don't think it'll be much of an issue," Thompson said. "The decision was made, we've just got to go with it. It's no point of us continually talking about it or whatever the case may be. ... We're not a team that runs the ball 35, 40 times a game, so if he's active, what happens? Does Guice get 15 carries and he gets three or five or the other way around and I only go in on pass plays? Then that gives up everything we do as an offense. It's a tough decision, definitely, to make and I know it's not a decision that Jay wants to make.

"I know that all the talk and narrative of us three being out there ... I don't know how we're going to be able to do it, honestly. I even talked to AP about that before."