Marshall pulled out of the Scotland squad with an elbow injury and will definitely be unavailable for City with former Manchester United youngster Heaton replacing him.
Kevin McNaughton picked up a slight knock in Sunday's 1-1 draw with Sheffield United and is doubtful and Paul Quinn could take his place in defence.
New signing Seyi Olofinjana is unavailable as is midfielder Darcy Blake who is away on international duty with Wales, however defender Gabor Gyepes can play after being left out of the Hungary squad to face England.
Jason Koumas is still short of match fitness but is expected to be included in the squad and may be introduced from the bench.
With a number of players out and with the Bluebirds having a small squad anyway manager Dave Jones is expected to give a number of youngsters a game, with Wales under-21 international Adam Matthews pushing for a starting place.