After spending around £250million on new players since his arrival two years ago, Mancini attracted scorn on Friday when he claimed City would struggle to fill their substitutes' bench for the FA Cup defeat to Manchester United.
As it turned out, City did come up with seven replacements, although they included Abdul Razak and Denis Suarez, who have just six first-team appearances between them, all but two from the bench.
And things may be even worse for Wednesday night's Carling Cup semi-final as David Silva is a doubt, in addition to Mario Balotelli and Edin Dzeko.
Gareth Barry does return from suspension, but the possibility of skipper Vincent Kompany serving a four-match ban at a time when resources are already depleted with Yaya and Kolo Toure on African Nations Cup duty has led Mancini to consider involving 17-year-old Dutchman Karim Rekik.
"All the people think we have a lot of players," said Mancini. "But we have 19, plus keepers. It is not a big squad.
"If we are unlucky and we have three or four players injured, like at this moment, we can have a problem. The club knows this."
The spectre of UEFA's Financial Fair Play regulations means Mancini may have to sell before he can bring anyone else in.
Yet the Italian claims there has, so far, been no movement on the potential departures of Nedum Onuoha and Wayne Bridge, who is likely to be on the radar of new QPR boss Mark Hughes.
And, whilst Carlos Tevez is now being courted by Inter as well as AC Milan, at present there is no deal.
It all adds to Mancini's sense of frustration, in a period he always felt would be pivotal to his side's chances of landing some silverware.
"I said four weeks ago that December and January would be crucial months," he said.
"Until three weeks ago we didn't have any injuries. Now, we have a problem.
"We have players injured and others who went to the African Nations Cup at a crucial moment.
"I am not happy about this but we can't do anything about it. If we don't get the players back we will play with the young players.
"If we don't have a central defender we will play with (Karim) Rekik."
Rekik will not be required to start against Liverpool at the Etihad Stadium on Wednesday night.
Even if Kompany's ban is upheld, Stefan Savic would be available to partner Joleon Lescott and Micah Richards also has plenty of experience in that role.
However, to lose the Belgian for four matches would place City in a perilous position, with the Toure brothers not due back until the middle of next month.
Little wonder therefore that Mancini is refusing to spend much time contemplating a failure with Kompany's appeal, even if history, and TV replays, suggest overturning a verdict seen by many as understandable from referee Chris Foy may be tough.
"My opinion has not changed," said Mancini.
"I am confident because Vinny only played 10 minutes.
"He was sent off for nothing. He has already missed one game.
"I don't think about this (being banned). It would be not correct if that happened."
Mancini also claimed he was right to point out that Wayne Rooney gestured to referee Chris Foy for Kompany to be sent off, even though the United star claims to only have been pointing out it was a two-footed tackle.
"I joked with Wayne Rooney. But he did it," said Mancini.
"Nani was there. He didn't say anything."