Both players were surprisingly missing from the squad that earned a 1-0 win against The Eagles on Tuesday night.
McFadden had sustained a slight groin strain during training on Monday whilst Quincy had sufferred a thigh strain.
Full-back David Murphy also had to sit out the win against Palace with a knee injury.
McLeish has said that he expects all three to have recovered from their respective injuries in time for Blues' next game at home to Sheffield Wednesday on Saturday afternoon.