Nottingham Forest duo Michael Mancienne and Kyle Ebecilio have been ruled out of action for six weeks.
The Reds have already suffered numerous injury problems of late, with a raft of key players being sidelined.
Ben Osborn, Robert Tesche, Britt Assombalonga, Andy Reid, Chris Cohen and Matty Fryatt are already missing from action, while Mancienne and Ebecilio - nursing knee and hamstring injuries respectively - will also not feature again until December.
"We have an unbelievable injury record," boss Dougie Freedman told BBC Sport. "I don't want to make an excuse but facts are facts.
"We have to juggle things around a little bit and possibly play certain players out of position. We need a bit of luck.
"Unfortunately over the summer we have had some bitter blows but we will continue to work with what we have got. We have to move on."