The Scotland international has trained all week but suffered a reaction to his calf injury on Friday and is now rated extremely doubtful by manager Peter Houston.
Centre-halves Darren Dods and Garry Kenneth, who have both been carrying minor knocks, will again be at the heart of defence.
Definitely ruled out are Francisco Sandaza, Scott Robertson (both groin), Lee Wilkie (knee) and Danny Cadamarteri (calf).
United (from): Pernis, Dixon, Dods, Kenneth, Webster, Watson, Dillon, Kovacevic, Buaben, Gomis, D Robertson, Swanson, Conway, Shala, Myrie-Williams, Daly, Goodwillie, Casalinuovo, Banks.
