In Mancini's short time at City alone, the Blues have suffered four agonising defeats to the men from Old Trafford, the latest coming last month when Wayne Rooney's wonder goal settled matters.
Now Mancini's side have another opportunity to redress the balance slightly after Micah Richards' 73rd-minute winner allowed them to stride past Reading and book a last-four meeting with Sir Alex Ferguson's men at Wembley on April 16 or 17.
"It is a great semi-final," he said. "You could see what it meant to the fans at the end. We are very close with all the top squads but we need to improve more and maybe next year we will be at the same level.
"But it is important that we played a good game at Old Trafford last time and we have a chance to win, like them."