This is the third consecutive week which Persa was listed as 'questionable' on the injury report.
While Persa has not played in either of Northwestern's first two games, he split reps with Kain Colter during Wednesday's practice. This was the first time he had done so this season.
Colter has filled in nicely as the starter, completing 73 percent of his passes, while adding 210 rushing yards and four rushing touchdowns.
Sophomore running back Adonis Smith was also listed on the injury report, marked as 'out' for Saturday's game. Smith was injured in the third quarter of the Eastern Illinois game.
For the second consecutive week, Jack DiNardo will be out. DiNardo was injured in the Wildcats' win over Boston College.
Also listed as 'out' on the injury report are Brian Arnfelt (foot), Jared Carpenter (wrist), Collin Ellis (hand), Roderick Goodlow (leg), and Tony Jones (leg).
Notably not listed on the injury report is junior running back Mike Trumpy, who missed last week's game with a head injury. Trumpy practiced during the week, and will play this Saturday.
Kickoff for Saturday's game with Army is set for 2:30 CT. That game can be seen on CBS College Sports Network.