David Wetherall is out of City's relegation fight until the new year.
The skipper faces a lengthy spell on the sidelines after tearing part of the medial ligament in his left knee against Watford.
Initial forecasts suggested Wetherall, an ever-present this season up to now, would be out for four to six weeks. But after tests by surgeon Steve Bollen, the centre-half is more likely to be missing for up to three months.
Wetherall, who must wear a knee brace for the next five weeks, admitted: "I'm absolutely gutted because I was feeling really good. I was feeling fit and strong and playing well.
"I had got a full pre-season in me and in the last six or seven games really started to get on top of the centre-forwards I was up against. It's massively disappointing that this has happened.
"But I can't do anything about it. I've got to rest it up for the next month and then it will be a case of effectively doing another pre-season.
"In the mean time I just hope that the rest of the lads can do well and get us out of the position we are in."
Rotherham's draw at Sunderland on Tuesday dropped City to second from bottom, five points clear of basement dwellers Wimbledon. And with only two points from the last seven games, the pressure is mounting for Saturday's home game against Nottingham Forest.
Wetherall added: "Things haven't gone well lately although I thought our performances up to Watford had been quite encouraging. But that was a bad day all round and we never got going, it was backs to the wall the whole time.
"But the lads have got to pick themselves up and put that behind them. Now we're playing a team that have just hit form but everyone has to keep believing that we can go out there and perform.
"Crewe have shown how quickly this league can change. By winning two in a row they are suddenly in the top half.
"It's just getting that first win and
stopping the slide before the gap
really opens up.
"I'm just so disappointed that I can't be there with them. But I've been told it's likely to be the new year and although I would hope to get back quicker I'm not going to rush anything."
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