Nebraska coach Bo Pelini says Taylor Martinez is doubtful for Saturday's game against South Dakota State and that redshirt freshman Tommy Armstrong Jr. is the probable starter.
Martinez has missed all week of practice because of a turf toe injury on his left foot.
Pelini said after practice Thursday that Armstrong and fifth-year senior Ron Kellogg III would take snaps against the Jackrabbits. Both played in the second half of the 56-13 win over Southern Mississippi on Sept. 7.
Pelini said the competition between Armstrong and Kellogg is close but that Armstrong had a ''tremendous'' week of practice.
The Cornhuskers (2-1) have an open date after this week and open Big Ten play Oct. 5 at home against Illinois.