Rapoport noted Guice underwent an MRI on Monday and that "the hope is he does not need surgery."
Guice enjoyed a standout career at LSU that led the Redskins to select him in the second round of the 2018 NFL draft. He tallied 2,868 yards from scrimmage and 29 total touchdowns across his final two seasons with the Tigers.
Injuries have derailed the early portion of his pro career, though. He suffered a torn ACL in his left knee during his first preseason game that forced him to miss the entire 2018 season. More recently, he suffered a hamstring injury leading up to this year's training camp.
Per Rapoport, the injury is to Guice's other knee, which he had injured in during his time at LSU.
If he's forced to miss further game action, Adrian Peterson, who was inactive on Sunday despite being healthy, once again figures to get the first crack at a majority of the snaps with the first-team offense. Chris Thompson will likely continue to handle third-down duties in Guice's absence.
Ultimately, the Skins should have enough backfield depth to overcome another Guice absence, but they will eventually want to see him stay healthy for an extended stretch. Every setback lessens the chances Washington will get enough return to match its original investment.