On Wednesday, City failed to find a way past Manchester United. On Saturday afternoon it was the same story against a Birmingham outfit hovering above the drop zone but committed to blanket defending the hosts were unable to get past.
Carlos Tevez did have a first-half effort ruled out for handball and James Milner's shot was kicked off the line by Stephen Carr at the start of the second period.
But disenchantment in the stands grew when Tevez was replaced by Gareth Barry in the final stages, forcing Mancini onto the back foot.
"I am frustrated as well," he said. "I wanted to win. I don't want to draw or lose.
"Carlos has had a little injury for two or three weeks and I felt if we took off that player we might have more chances to score.
"But if you think I put four strikers on and we score four goals, it is not true.
"All supporters are like this, in England and Italy. I must think like a manager. We can play wide, get the ball into the box, then we can score.
"Supporters just think why don't you put more strikers in the box, two, three, four, five."
The absence of Emmanuel Adebayor with a heel injury and Mario Balotelli through suspension led to Mancini introducing Roque Santa Cruz midway through the second half.
Yet £18million Brazilian forward Jo remained on the bench as Tevez made his way off, raising a rueful eyebrow as he took his place in the dugout.
With just one win in five Barclays Premier League games - and no league goals on home soil since the beginning of October - questions are being asked of Mancini, by supporters if not the club's owners.
The Italian flew back home on a family visit this evening, although he insists he feels under no pressure.
"Which pressure? For what?" he said. "You continue to say I am under pressure. Which pressure? Because some supporters say I did not put two strikers on, or journalists say I am too defensive?
"I am not under pressure. We are in fourth position. We have some problems. Since the start of the season it has been the case that if Carlos Tevez doesn't score, no-one does.
"We must improve that. But we have only played 13 games. When I have all my players and we have the right balance, then maybe we play better."
Ironically, Birmingham manager Alex McLeish seemed more relaxed even though his side are struggling at the wrong end of the table.
It was a job well done for the visitors, with the former Scotland chief admitting he would have taken a point before kick-off.
"I was never comfortable," he said. "The second half in particular was a bit scary but the longer the game went I felt we could just nick something."
McLeish confirmed midfielder Craig Gardner suffered an ankle injury, which he had hoped to run off but found the pain was just too severe.
"He was struggling even before City came out for the second-half," said McLeish. "But we stood firm. Everyone put a shift in for us.
"We know we have a big fight in this league but we are not getting panicky and paranoid looking at league tables in November."