The rookie signal-caller suffered the injury during the fourth quarter of Sunday's NFC wild card round playoff loss to the Seattle Seahawks. He was removed from the game after being helped off the field.
The newspaper, citing several people with knowledge of the magnetic resonance imaging test results, said Griffin has suffered partial tears of the anterior cruciate and lateral collateral ligaments of his right knee.
Redskins Coach Mike Shanahan didn't specify the extent of Griffin's injury during a press conference Monday, saying only he was set to be examined Tuesday by orthopedic surgeon Dr. James Andrews in Florida.
The coach said the exam would determine whether the MRI results showed new or previous injuries -- Griffin also suffered a torn ACL in the knee while playing for Baylor University in 2009.