With his side losing 3-1 against Ajax on Wednesday, Mancini hauled off Joleon Lescott to play three defenders, and they immediately conceded again.
In his post-match interview Micah Richards claimed his team-mates did not like the system, but Mancini said on Friday: "If you are a top player it is not important what system you use. If you don't understand a system like that, you cannot play for a top team."
He went on: "What Micah said is not important. He answered a question. I understand people want to write about it, but to me it doesn't matter.
"Maybe Micah doesn't know because it his first game for two and a half months."
City must now win their final three games to stand any chance of reaching the knock-out stages.
Mancini has described that as being a "miracle" scenario. However, he does not feel it is a time to just give up.
"This is an important season for us," he said.
"If we allow one defeat to alter that we would be really weak. Strong teams can lose a game but it is important you understand the reasons, and what mistakes were made. You can learn from this and improve for the next game."
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