Guice was injured in Washington's preseason opener at New England on Thursday night.
Selected in the second round of this year's draft, former LSU standout Guice went down awkwardly as he was tackled from behind on an impressive 34-yard scamper negated by a holding penalty. He hung around the locker room with teammates after the Redskins' 26-17 loss, sucking on a lollipop at his locker as he scrolled through his phone.
Early Friday, the initial thought was Guice had suffered a sprain. He has made a quick first impression on his Redskins teammates, including quarterback Colt McCoy, who said Guice has been "fun to watch" and is a "great player".
The 41-year-old's current deal has two years worth $41 million left that runs through the 2019 campaign, which has left the door open to what the Patriots will do after this upcoming season as he will be in his final year.More news: Washington demands probe into Yemen bus strike
Several scouts had questioned Guice's durability going into the draft.
Instead, Guice's National Football League career starts with a medical redshirt. He played all 16 games last season and earned NFL MVP honors after tossing 4,577 passing yards and 32 touchdowns.
In camp, Guice had been splitting first-team carries with Kelley and Samaje Perine. Coach Jay Gruden has said there was competition for the No. 1 job along with third-down back Chris Thompson. "He's one of those guys we're expecting a lot out of him".