Cubit said Monday that the starting back was due to see a doctor later Monday. But Cubit said that he wasn't optimistic the right-shoulder injury would allow Ferguson to play.
Illinois (4-1, 1-0 Big Ten) lost Ferguson in the first quarter of last Saturday's 14-13 win over Nebraska. The senior has 397 yards and three touchdowns on 71 carries.
Freshman Ke'Shawn Vaughn took over for him Saturday and was the only other Illini back to carry the ball. Vaughn had 98 yards on 24 carries.
Cubit said Illinois will need little-used junior Henry Enyenihi to help pick up the rushing load at Iowa (5-0, 1-0).