Darren Ambrose is a major doubt for Palace.
The midfielder suffered a knee injury during Saturday's 2-0 win over Burnley and Palace are awaiting the results of a scan to determine the extent of the damage.
Strikers Glenn Murray and Steffen Iversen are also on the injured list.
Summer signing Murray missed out against Burnley after twisting his ankle at Peterborough and is unlikely to be fit while former Tottenham frontman Iversen has a hamstring injury
Right-back Nathaniel Clyne is still missing with a foot injury, left-back Lee Hills has knee trouble and midfielder Alex Marrow is building up his fitness after a long-term ankle problem.
Andy Thorn is sweating on the fitness of two unnamed midfielders.
Thorn chose not to reveal the identity of the pair who picked up knocks in Saturday's 1-0 defeat at Birmingham, but with only Sammy Clingan, David Bell, Gary McSheffrey and Gael Bigirimana featuring in midfield at St Andrew's it no doubt provides the Sky Blues boss with another headache.
Gary Deegan (thigh), Carl Baker (suspension), Clive Platt (knock), Richard Wood (thigh) and Jordan Clarke (knee) continue to miss out along with Freddy Eastwood (hamstring) and defender Ben Turner (knee), although it is hoped the latter pair could make a tentative return to training by the end of the week.
Speaking at the club's Ryton training ground on Monday afternoon, Thorn said: "We got a few knocks on Saturday so there's a few having an easier day today because obviously we want everyone ready for tomorrow
"There's a few (major doubts) for Tuesday, there's a couple who could be struggling but we'll just wait and see. Everyone will travel down anyway and we'll just play it by ear.
"With the injuries we've got now, we're 14 players down from last season and the boys that went. That's not an excuse it's something we have to deal with and get on with, we'll do that and we're looking forward to Tuesday."
