Peterson went down with the injury during the opening minutes of the third quarter when he was hit in the left leg by Redskins safety DeJon Gomes as he burst through a hole, his left knee bending inward.
Peterson said he knew "it was something bad" the moment he was tackled.
"I'm trying to stay as positive as I can," Peterson said as he stood on crutches in the locker room.
The serious injury would likely sideline Peterson, who before the season began signed a seven-year, $100 million contract extension, for about nine months.
Simpson sticks the landing
Wide receiver Jerome Simpson, a hardly known four-year veteran from Coastal Carolina, leaped into immortality in the Bengals' win over the Cardinals.
With 2:46 to go in the first half and the ball on the 19-yard line, Simpson ran a crossing route, caught a sideline pass from Andy Dalton, and then - from the 3 - somersaulted over linebacker Daryl Washington, who was bearing down on him at high speed.
Incredibly, Simpson landed on his feet. If artistry were part of the scoring, this touchdown would have been a 10.
Bush now works for a living
After more than five years in the league, Reggie Bush has gone over 1,000 yards rushing for the first time in a season. Bush, in his first season with the Dolphins after being the Saints' boutique back for five years, reached that milestone with an 8-yard burst in the first quarter against the Patriots.
This is his first season as a full-time running back. And we mean full-time: He finished the day with 22 carries for 113 yards. His previous season high was 581 yards in 2007.
Akers breaks record
