Centre-half Paul Digby will be out until January with a knee problem, while midfielder Giles Coke has undergone a further knee operation and will now be sidelined until the end of next month.
Digby, 21, picked up his problem while playing for the U23s last month, while 30-year-old Coke has now had three knee operations since initially suffering his knee injury in February at QPR.
"Diggers has a heavily bruised knee and it’s been in a brace for the last two weeks,” physio Matt Byard told the club site.
"It's probably going to be another three weeks or so before he will be back training.
"Unfortunately for Giles, he has torn another part of his cartilage in his right knee and had surgery on Tuesday.
"He had returned to training and was making good progress but we now expect him to be out until the end of January.
"Repairing cartilage is always the more preferred option if possible to reduce the risk of osteoarthritis occurring later.”