In the eyes of Manchester City fans, above United's numerous successes and world-wide appeal, perhaps the one aspect about their near neighbours that cuts so deep is a Stretford End banner that started might have started as friendly banter between the two clubs, but had now turned into an obsession in both camps.
It may read '35 years', but until the Old Trafford club take them seriously as a dominant force, it may be decades until the pain wears away.
However, this weekend, for the first time since 1981, City have their chance to set the record straight. The team they ousted in the race for the fourth Champions League spot, Tottenham Hotspur, defeated The Blues after a replay 30 years ago, five years after their last major trophy success, the League Cup.
Now, with the club much changed since the days of Ranson, Bennett and Hutchinson, City face Stoke City, themselves revelling in the novelty of an FA Cup final appearance.
After spending in excess of £200 million since taking over from Mark Hughes, Roberto Mancini is under pressure to deliver his first trophy at Eastlands, not only from the supporters who have lived in United's shadow for so long, but from the club's wealthy owners, who will want a return on their hefty investment.
David Platt has known and worked with Mancini for over 20 years, and admits it's the Italian's winning habit that keeps him going.
"He just enjoys winning, that's his desire; everything he does is to improve because he knows that if we improve then we have a better chance of winning and that’s what drives him on," Platt said. "I know that whatever happens on Saturday he’ll turn his attention to Tuesday and plan on catching Arsenal."
Something that might have gone unnoticed beneath the talk of the 'Blue Moon rising' and fabricated transfer rumours is the team spirit Mancini has created among his cosmopolitan squad, so much so that many of the players will devote a win on Saturday, to him.
"I think he’s going to show that he’s worth paying because he’s really focused on bringing success to this football club, he’s been working hard and if he were to win the FA Cup it would be fantastic for him for the players for the fans ad I think it will be a special day for the club," said Patrick Vieira.
You could forgive Mancini for feeling the pressure going into the big day - particularly given the ruthlessness of how the Abu Dhabi United Group helped snatch Robinho on deadline day in 2008, and how they sacked Mark Hughes after guiding the club to sixth in the Barclays Premier League.
Much has been made of this season's targets, and whether just Champions League qualification would be sufficient for the ambitious owners, or whether a trophy is also needed, remains to be seen. If Mancini is to be believed, the result of the battle with Stoke could be decisive.
"The target at the start of the season was the Champions League, that was the first important target for the club, and after that we wanted to go in one of the two finals that we can play, the Europa League or the FA final," Mancini said.
Despite him considering The Potters as "a strong team", there's no doubt that City will be favourites at Wembley. Granted, their record against Pulis' men doesn't read well - one win in six matches - but with the wealth of talent to call upon and Stoke's bad luck with injuries means the pressure to produce, as if possible, is swelled further.
Many of City's players are looking to inscribe their names in the history books, and one man who has that honour and was part of the great Blues side of the 1970's, Mike Summerbee, doesn't believe pressure exists for the experienced Mancini.
"I don’t think he’s been under any pressure, he’s won two Serie A’s so he’s a very experienced manager," he said.
"He’s know exactly what he’s doing and I wouldn’t say it’s pressure at all. People have asked him to do something and he’s gone about it in such a professional way and one of those things was the Champions League."
Against the throws of Delap, the strength of Jones and tactical nonce of Pulis, Mancini may need every ounce of that experience. After all, the owners and fans would demand as much.