Aberdeen midfielder Jamie Smith will miss the CIS Insurance Cup semi-final with a hamstring injury.
Richie Byrne has a similar problem and fellow defender Stuart Duff is ineligible to face his former club.
Dundee United have lost keeper Grzegorz Szamotulski and skipper Barry Robson since the tie was postponed last week.
Jim O'Brien, Danny Swanson and Danny Grainger are cup-tied and Mark de Vries lacks match fitness, although the new striker may be risked from the start.
Noel Hunt, Willo Flood and Sean Dillon will all undergo late fitness tests for Craig Levein's side.
http://news.bbc.co.uk/sport1/hi/football/scot_cups/7226724.stm