Pryor suffered a concussion in Week 3 against the Denver Broncos. He passed his concussion test and resumed practice late in the week, but his concussion symptoms resurfaced late Saturday night.
Matt Flynn will start in Pryor's place for the Raiders. Oakland trade for Flynn over the offseason, but Pryor won the quarterback competition in training camp, marking the second straight preseason in which Flynn has lost a quarterback competition.
Pryor played well in the Raiders' first three games before suffering the head injury against the Broncos. The Raiders may have their long-term answer under center in Pryor, so it makes sense that they would play it safe and keep him out of this game after his injury.
Flynn will be making his first start since leaving Green Bay, where he had a decent amount of success in limited action.