Martinek will be aided by the Scarlet Knights' bye this week, and likely will be held out of practice.
"I thought after the game that he'd be ok. I'm not so sure anymore," Schiano said. "We have to wait and see here He won't do much this week. I know that."
Martinek was injured late in the fourth quarter of Saturday's win at Florida International when a defender rolled onto his ankle during a tackle.
After the game, Martinek told ScarletReport.com the sprain was in the lower portion of his ankle, and it was too early to tell if he would be ready for the Tar Heels.
He leads Rutgers with 147 yards on 34 carries, and will spend the week rehabbing and resting the ankle.
"It's not the worst thing in the world for him to get a little break, as long as he's going to be ok next week," Schiano said. "I'm not so sure that's going to be the case. "We're going to have to wait and see."
If Martinek is out or limited, it likely will mean more carries for freshman Jordan Thomas. Also, it could give De'Antwan Williams opportunity to break into the rotation, or give Kordell Young the chance to expand his role from third-down back.
As the Scarlet Knights try to fix what ails the offensive line, Schiano said the bye will be use to create a competitive week of practice as he mixes things up from the usual game-preparation week.
"I think what it will be is it will be more good against good, and when I say that, I mean (No.) 1 defense (vs. No.) 1 offense and so on," he said. "I think that could create a little bit of a training camp environment where guys have an opportunity to shine and move forward."
More on Mohamed
Sophomore receiver Mohamed Sanu led the team in rushing (44 yards), reception (4) and threw a 24-yard touchdown pass at FIU.
"Mo is definitely a special talent," Schiano said. "We ask him to do a lot. …I think Mo is going to continue to get better and better because there's still a lot of technique things he can refine and become even more efficient. But what you can't coach is his athleticism, his toughness, his desire to play the game, his will to prepare."
So, what are some areas of improvement for Sanu to concentrate on?
"Blocking angles, route-running, high speed decision making, those kinds of the things, as well in the Wildcat package," Schiano said. "The more times you see, you read it …it's option football a lot of the times, and you have to be able to read your keys and execute at a high speed."