Jerome Thomas (back) and Filipe Teixeira (thigh) both missed training on Thursday and are doubts, while fellow midfielder Robert Koren has gone to see a specialist to get a full diagnosis on a hernia problem.
Left-back Joe Mattock is unlikely to involved having been stretchered off during last week's 4-1 victory over Bristol City with a badly-bruised foot.
Fellow defender Shelton Martis has also reported flu-like symptoms, similar to those Roman Bednar is still struggling with after he was forced to pull out of last Saturday's clash.
The news will come as a blow to head coach Roberto Di Matteo who has already stressed the importance of doing well on the road in the forthcoming double-header against Wednesday and Derby.
Long-term trio James Morrison (heel), Ishmael Miller and Neil Clement (both knee) also continue to miss out.