The initial thought was a sprained MCL, suggesting he'd miss a few weeks.
Guice was expected to be the Redskins' starter after they selected him 59th overall in the draft.
For fantasy players who already drafted Guice, it might feel like your season is already over.
Before his injury, Guice was having a strong training camp, taking snaps with the first unit and displaying the same "violent" running style that he was known for. Washington will now rely on Rob Kelley and Samaje Perine to be their primary backs, while Chris Thompson will continue his role as a third-down specialist.
White House dismisses former Trump aide who branded him ‘racist’
That something else might be Omarosa Manigault Newman - the former contestant on The Apprentice and former White House aide. The Trump campaign declined to comment on Manigault Newman's description of the deal Lara Trump supposedly offered her.
It's a major blow for the Redskins going into a critical season for Jay Gruden's offense directed by new quarterback Alex Smith. But there are other running backs, such as Ronnie Brown and Edgerrin James, who were never the same after the injury.
Brady, the NFL's reigning Most Valuable Player, turned 41 on August 3 and is entering his 19th season.
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. The Redskins also announced tight end Manasseh Garner suffered an ACL injury during Thursday's game and will also miss the 2018 season.