Scamacca arrived in a £30.5m deal from Sassuolo last month but did not feature for the Hammers in pre-season.
“Gianluca only joined us recently so he’s a bit late,” Moyes said. “I don’t expect him to be available this weekend. We made some good signings this summer, but we also had one or two injuries, which doesn’t help.
Moyes did not specify which players the concerns are over, but he will certainly be without the signing of centre-back Nayef Aguerd, who is out for ten weeks after undergoing surgery on an ankle injury suffered in the defeat of pre-season against Rangers.
Angelo Obgonna is continuing his comeback after missing most of last season with an ACL injury but is still ‘three or four weeks’ away from being in contention.
“He’s playing this afternoon for the U23s,” Moyes said on Friday. “He played his first 90 minutes last week. He’s doing great but he’s not ready to be considered for the first team yet.
In goal, Moyes has an important decision to make, either to stay with last season’s No.1 Lukasz Fabianski or to hand over the gloves to Alphonse Areola, who was cup goalkeeper last season but has now switched on loan from PSG permanently.
West Ham predicted XI: Fabianski, Coufal, Dawson, Zouma, Cresswell, Soucek, Rice, Fornals, Lanzini, Bowen, Antonio.