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.
Things may be even worse for Wednesday's Carling Cup semi-final first-leg encounter with Liverpool.
Star man David Silva is a doubt, in addition to Mario Balotelli and Edin Dzeko.
And although Gareth Barry does return from suspension, skipper Vincent Kompany is starting a four-match suspension after the FA rejected his appeal against the red card he received against United on Sunday.
At a time when resources are already depleted due to the absences of Yaya and Kolo Toure on African Nations Cup duty with the Ivory Coast has led to Mancini raising the possibility of 17-year-old Dutchman Karim Rekik being involved.
Which just goes to prove City's squad is not quite as deep as some people imagine.
"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 being invoked 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 Milan as well as AC, 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."
Even with Kompany missing, Rekik will not be required to start on Wednesday night.
However, Stefan Savic, who only celebrated his 21st birthday on Sunday, could.
Signed for £6million from Partizan Belgrade in the summer, Savic has started just one Premier League game - at QPR in November when City emerged 3-2 victors in a thrilling encounter.
In addition to that, the Montenegro international has amassed just 94 minutes' top-flight experience in six substitute appearances.
Yet he could be the man who partners Joleon Lescott after the FA came down on the side of Chris Foy over the contentious decision to dismiss Kompany for his 12th minute foul on Nani.
Mancini is bound to be annoyed by the verdict, even if it was fairly predictable.
"My opinion has not changed," said the Italian on Tuesday morning, prior to the announcement.
"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."
