New England Patriots running back Dion Lewis is scheduled to undergo an MRI on his injured knee, but the ACL is reportedly "loose," according to ESPN reporter Adam Schefter.

Lewis' knee reportedly has no swelling, but a loose ACL is very bad sign and swelling for an isolated tear doesn't usually happen until overnight, according to former NFL Physician David J. Chao. Lewis signed a contract extension last month, and was having the best NFL season of his career. 

Lewis has rushed for 220 yards this season and has scored two rushing touchdowns. The Patriots running back is key for New England on passing downs, as he has 32 receptions on the season for 349 yards with two touchdowns. Quarterback Tom Brady knows how important Lewis is to the Patriots, and said he is "hoping for the best" after the game, according to Patriots reporter Mike Reiss.

The Patriots improved to 8-0 with another impressive win this weekend, beating the Washington Redskins 27-10. With Lewis out, running back LeGarrette Blount had a productive day rushing for 129 yards and a touchdown. It's unclear the extent of time Lewis will miss, but it seems that it may be a significant injury. Head coach Bill Belichick will look for Blount and Brandon Bolden to carry the load with Lewis injured.