RG3 sustains concussion; Polamalu re-injures calf

Redskins rookie Griffin sustained a "mild concussion," according to coach Mike Shanahan, when he took a shot to the helmet while scrambling to try to avoid a sack during Washington's 24-17 loss to the Atlanta Falcons. Griffin left the game about 10 minutes in to the second half and did not return. He also was treated for a cut on his chin.

"He wasn't sure what quarter it was in the third quarter. So at that time, when he wasn't really sure what the score was, what the quarter was, we knew he had a mild concussion — at least according to the doctors," Shanahan said.

Team spokesman Tony Wyllie said Griffin was examined by a neurologist in the locker room before being sent home from the team's stadium and will be evaluated again Monday. NFL rules require a player diagnosed by the team medical staff with a concussion to sit out the rest of the game. The player also can't return to practice or game action until a team doctor and independent neurologist clear him.

About three hours after the game, Griffin wrote on Twitter: "I'm ok and I think after all the testing I will play next week."

Cassel, Kansas City's quarterback, left with a head injury in the fourth quarter after getting hit by Baltimore's Haloti Ngata while attempting a pass. Cassel remained flat on his back for several minutes before getting helped up and walking off the field under his own power. Backup Brady Quinn entered the game to a round of applause.

Cassel was 9 of 15 for 92 yards and two interceptions when he left the game won by Baltimore 9-6.

Polamalu left Pittsburgh's 16-14 win over the Philadelphia Eagles in the first quarter. He limped off following a fumble by Eagles quarterback Michael Vick. The 2010 NFL Defensive Player of the Year watched the entire second quarter from a seat on the bench and did not move. He was replaced by backup Ryan Mundy.