Oakland quarterback Jason Campbell missed one series after appearing to hurt his right leg in the first quarter against Kansas City on Sunday.
Campbell stayed down for several minutes after being shoved out of bounds on a third down play by Kansas City's Tamba Hali and then got up and sat on the bench.
Trainers appeared to be working on his right knee. He was walking around a few minutes later when backup Kyle Boller came out to lead the Raiders in their next series.
Campbell was back under center when the Raiders got the ball back right before the end of the first quarter, with the Chiefs leading 3-0.