Steelers safety Troy Polamalu left Sunday night's 13-9 win over Kansas City after his head banged into the knee of offensive tackle Steve Maneri.
The team said Polamalu had a "blow to the head" and did not return.
Polamalu, who had been dealing with some sore ribs, looked a bit wobbly as he got up. He was helped to the sideline by trainers and did not return on the Steelers' next defensive series.
Polamalu, Pittsburgh's defensive leader, was a bit wobbly when he stood up and Tomlin said after the game that he was experiencing "concussion-like symptoms."