"We'll have to wait and see," O'Brien said during Tuesday's news conference. "If they don't practice by Thursday or Friday, they'll probably be out of the game. But right now ... it's probable."
Morris was carted off the field in the second half with his right ankle wrapped in ice, and Belton sprained his left ankle late in the third quarter. Morris saw limited practice Monday and was in the training room, players said, but Belton's status was unknown.
If Belton cannot go Saturday, fifth-year senior Derek Day -- who rushed for a career-high 36 yards against Ohio -- will take his place. Zach Zwinak, Akeel Lynch and Curtis Dukes will compete for time at backup.
"We hope [Belton] is back," fullback Michael Zordich said. "But if he's not, Derek Day isn't exactly a sleeper. He showed a lot on Saturday. He can run the ball very well and understands his routes and protections."
Morris tweeted Monday night he would return in time for Saturday, and true freshman Da'Quan Davis would likely fill in for him at cornerback. When Morris left Saturday, Davis came in and had a costly penalty but also broke up a touchdown pass.
O'Brien said he'll better know whether the pair can play by Thursday.