From The Associated Press:

ALLEN PARK, Mich. (AP) -- Detroit Lions receiver Calvin Johnson limped off the field and the team's training staff treated his right knee on the sideline Sunday.

He was hobbled as he tried to walk after the Pittsburgh Steelers beat Detroit 28-20.

Johnson was running a route across the end zone in the first quarter when he pulled up and appeared to be in pain. He left the previous game at Chicago with a thigh injury that slowed him during practice.