Morison is struggling with a calf injury after being withdrawn at half-time during last week's home draw with Peterborough and missed the derby defeat to Huddersfield on Saturday.
Manager Neil Warnock was without both first-choice forwards against the Terriers - Ross McCormack missed out with a head injury - and was forced to hand a first start to Habib Habibou.
"Steve is out with his calf, but hopefully it's not too serious because obviously Steve is a big threat up there," Green told Press Association Sport.
"He causes defenders all sorts of trouble with his size and mobility and he'd just hit a rich vein of form getting the two goals at Palace.
"Hopefully we can get him back and keep him fit."
