Midfielder Terry Dunfield (shoulder) is sidelined for eight to 10 weeks, defender Mike Jackson (bone bruising) and goalkeeper Glyn Garner (shoulder) are awaiting results from scans before the club know how long they will be out, while striker Omer Riza (ankle) is a long-term absentee.
Goalkeeper Chris Neal (groin) and midfielder Craig Disley (knee) should return to training in the next couple of weeks.
Matters could have been even worse for Simpson, who was in the same situation for the 2-1 home defeat to Bradford last weekend, but midfielders Jake Simpson and Joss Labadie have both recovered from head/face injuries.
Striker Kris Bright (ankle) was taken off as a precaution in the 3-0 reserve-team victory at West Brom in midweek and he is okay to feature.
Jake Robinson grabbed a brace in the impressive triumph while Andre Gray netted the other and Simpson has hinted their displays, plus those from others involved, could see them included on Saturday.