Green Bay Packers outside linebacker Aaron Kampman played most of Sunday's loss at Tampa Bay with a concussion before leaving the game in the fourth quarter. His availability for the Packers' upcoming game against Dallas is unclear.

Kampman said Monday he took a hit to the left side of his head on the fourth play of game and still wasn't feeling quite right Monday.

An eight-year veteran, Kampman says this isn't the first concussion of his career but he hasn't had one recently.

Packers defensive coordinator Dom Capers says he and other coaches didn't realize Kampman had been injured until late in the game. Capers says players must recognize when they're not feeling right and tell coaches.