Sophomore quarterback Kain Colter will make his third start of the season against the Black Knights. Persa has missed the first two games as he continues to rehab from Achilles tendon surgery.
Northwestern has listed Persa as questionable on its injury report for each of the first three games.
Persa, who has been practicing for six weeks, said this week that he was still awaiting clearance from team doctors.
Adam Rittenberg covers Big Ten football for ESPN.com. He can be reached at email@example.com.