Jamie Lawrence could be out of action until November.
City's Jamaican international midfielder was undergoing x-rays on a suspected broken right ankle he suffered in a tackle with Stoke captain James O'Connor.
Physio Steve Redmond said: "We're getting it confirmed but we fear that it is broken which is going to mean Jamie missing for at least the next eight weeks."
Lawrence's injury in only the third game of the season is the sort of hammer blow Nicky Law has been dreading and stretches the club's thin playing resources.
Law also fears that Gus Uhlenbeek will not sign up after the Dutchman baulked at an improved contract offer.
City have put a "take it or leave it" deal on the table but the defender, who has been performing on non-contract terms, seems reluctant to agree.
Law said: "We've offered Gus a contract and he's turned it down. We've made a revised offer and I don't think he's overly-impressed with that either.
"If I'm honest, that's about as far as we can go. We just haven't got the money anymore after being through what we have been.
"Times are tough and we have to do the best we can. Jamie came out on crutches for the second half but we've got to buckle down as a group and get on with it."
Law accused City of beating themselves after gift-wrapping Stoke their 2-1 victory at the Britannia Stadium, which was teed up by a howler from goalkeeper Gary Walsh.
He said: "I'm not trying to make Gary feel any worse than he does, he knows what he's done. It would be too easy to just say it's Gary's fault but equally we have to look at the whole picture and ask if we did enough - I don't think we did.
"You can't go anywhere at any level of football and expect to get something when you give away goals like we did. But I could be equally critical at the other end.
"I thought our fans were excellent. They had ample chance to get on our backs but didn't."
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