Allar left the game against Wisconsin at the end of the first half.
Donkoh was seen during the practice viewing-session on Wednesday.
Carter has 9.5 tackles-for-loss and four sacks in his first season at defensive edge.
With a host of other attractions coming to Happy Valley on Saturday, James Franklin is solely focused on the product inside the Lasch Building.
With Drew Allar questionable, Beau Pribula and Ethan Grunkemeyer are preparing for action on Saturday.
Camp Randall Stadium delivered as one of the top college football venues in the Big Ten.