Departing Peterborough manager Jim Gannon has defensive problems ahead of the visit of Bristol City.
On-loan Wolves full-back Mark Little had been filling in at centre-half for the past two games but lasted just 26 minutes against Scunthorpe in midweek before hobbling off with a hamstring injury.
He is starting a four-week lay-off so Gannon will have to move Exodus Geohaghon back into the defence after a spell in midfield.
Record signing Ryan Bennett remains sidelined with his ankle injury while fellow centre-back Craig Morgan is also out with an ankle problem.
Posh also have problems in attack as on-loan Brighton forward Liam Dickinson remains a doubt with a hamstring injury and Aaron Mclean is out for the rest of the season after having knee surgery this week.
Gannon - who decided this week to leave the club at the end of the season - will be looking for a positive response to the 4-0 drubbing in midweek which left Posh 12 points adrift of safety.
Caretaker manager Keith Millen is poised to hand on-loan Plymouth defender Gary Sawyer his debut at London Road.
The Robins swooped to land the 24-year-old until the end of the season on loan deadline day and he will go straight into the squad as Millen ponders his options in defence.
Lewin Nyatanga pulled up in the warm-up before the 5-3 midweek win over Barnsley with an Achilles injury and will miss out.
Nyatanga will join fellow defender Jamie McAllister on the sidelines after he suffered a recurrence of a calf injury against Newcastle last weekend and will miss the next four to six weeks.
Midfielder Marvin Elliott limped out against Barnsley after picking up an injury and is doubtful, while a handful of other players are also nursing various bumps, knocks and bruises meaning Millen will leave it as late as possible before assessing which 18 to go with.
Defensive duo James Wilson and Jamie McCombe remain on the sidelines with knee injuries as City look to record back-to-back wins for the first time since October.M
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