The Manchester United's irritation with Chelsea counterpart Rafael Benitez goes back to the Spaniard's days at Liverpool and that infamous rant in 2009, when he claimed it was a "fact" that Ferguson manipulated referees and received preferential treatment from the Football Association.
Ferguson has never forgotten the attack and when Benitez turned up at Chelsea following the dismissal of Roberto Di Matteo earlier this season, he labelled the former Valencia boss as "very lucky" for being given the chance to take over two Champions League-winning teams, having also replaced Jose Mourinho at Inter Milan.
It has not proved so lucky for Benitez, who has failed to win over sceptical Chelsea support, seen lingering title ambitions quashed, crashed out of the Champions League and is now in a desperate scramble to secure a top four berth.
Benitez has railed against the club's hierarchy for naming him an "interim manager" and he now accepts there is no chance of getting the job on a full-time basis.
And now he faces a trip to Old Trafford for Sunday's FA Cup quarter-final.
"I'm not going to kick anyone when they're lying down," said Ferguson.
"It's not my style. My concern is Manchester United. What happens at Chelsea doesn't really affect me.
"Chelsea have a terrific record in the FA Cup, probably the best of any team in the last decade.
"It doesn't matter when you play Chelsea or who's in charge, we'll have a hard game."
Yet Ferguson concedes such a marquee contest is exactly what his wounded troops need following the crushing disappointment of their Champions League exit to Real Madrid in midweek.
The entire United camp is convinced the blame lies at the feet of Turkish referee Cuneyt Cakir, whose decision to send off Nani turned the whole tie Madrid's way.
However, Ferguson concedes nothing can be done about that now.
And he is demanding a fighting spirit from his squad as they look to book a Wembley semi-final berth and take another step towards their first triumph in the tournament since 2004.
"I've cleared my mind," he said.
"It's just another day in the history of our club. Not a good day, but another day.
"My job now is to galvanise the troops.
"There are a lot of things you can do when you lose a game. One thing we don't do is give in.
"We get up off our backsides and make sure we're ready for Sunday because we owe the fans a really good performance."
Ferguson once again made the point that the vast majority of his squad have not tasted success in the FA Cup.
And none of those who have - at least for United - will be involved.
Darren Fletcher has already been ruled out for the season, Paul Scholes is still sidelined by a knee injury and Ryan Giggs will be rested after his magnificent performance on the right wing against Real.
Robin van Persie picked up a winners' medal for Arsenal in their 2005 shoot-out victory over United and needs to find some form after slipping below the high standards of earlier in the campaign.
Van Persie has scored once in eight games and has been overtaken in the Premier League Golden Boot standings by Luis Suarez.
If Van Persie does play, that takes away one of the positions Wayne Rooney could occupy.
Most of the attention will be focused on whether Rooney appears or not, although, as Ferguson pointed out, work has had to be done with Nani due to the guilt he feels at United's European plight.
"Nani was obviously disappointed and we have to get rid of that feeling of guilt he maybe has," said Ferguson.
"I don't think he did anything wrong and that's the message we'll give to him."