Under Mancini, City have develop a reputation for being solid defensively but, perhaps unfairly, rather limited going forward. And even though rivals Manchester United are without Wayne Rooney, the Italian has no intention of offering Manchester United an easy route to goal.
"Every City fan will be happy if we win," said Mancini. "If we do that 1-0, it is not important. If we win on penalties it is not important. But if we attack and leave United to have ten chances, it is stupid."
He added: "All my players should understand very well this is a big moment for us, We can change the history of the club. The first trophy is the hardest but it is time for Manchester City to win something," he admitted.
They will have to get over the next hurdle without their talisman, though, as skipper Carlos Tevez has been ruled out with a hamstring injury.
"It is very difficult for him and us, that we should play this game without him," said Mancini. "But we could not take a risk. We can still do a good job without him. We have other players and I trust all of them."
That includes firebrand Mario Balotelli, who will be required to assume additional responsibility in Tevez's absence.
"He knows it is an important game for him," said Mancini. "If his focus is on the game, he can do everything."
City have received some good news with the return of full-back Micah Richards to training. Only three weeks since he pulled a hamstring on England Under-21 duty, Mancini accepts the young full-back cannot be 100% but acknowledges his return would be a boost.
"Micah is not fully fit but this is normal," he said. "But he is an important player for us and has trained well this week - he can play a good game."