There was only one flicker of irritation from Roberto Mancini and it was disguised with a smile after he was made aware how Sir Alex Ferguson, that master of the wind-up, had been taking a keen interest in the number of refereeing decisions that have gone in Manchester City's favour. Half an hour earlier, across the Carrington fields, past the stables and along the thin country lane to Manchester United's training ground, Ferguson had picked up on David Moyes's theme from last weekend and noted, conspiratorially, the frequency with which City had been awarded penalties.

"Twenty-one in the last year, isn't it?" the Manchester United manager asked. "If we were to get that number of penalty kicks there would be an inquiry in the House of Commons. There would be a protest."

Mancini leant back in his chair and delivered his riposte. "But I remember very well last year," he said. "[Ashley] Young, when he went swimming …" Then the manager of the Premier League champions clasped his hands together and stooped his head in the manner of someone diving off the top board. His tone was one of exaggerated puzzlement. "I think it was four or five times in the last 10 games and he [Ferguson] didn't say nothing."

That is the beauty of holding your press conference straight after the other guy: you always get the chance to have the final word. Alternatively, it may just be that City are growing a little weary of all the "noisy neighbour" stuff – or "screaming" neighbours, as Ferguson had adapted it on this occasion (suggesting the volume had gone up rather than down) – when most of the little digs and put-downs these days seem to originate from Old Trafford. Ole Gunnar Solskjaer, once of the parish, continued the theme by describing City as being United's "little brother".

Perhaps, though, Ferguson may want to look a little more closely at the penalty statistics when the 21 awarded to City in the league have actually come since the start of the 2010-11 season. United can hardly feel harshly done by when they have had precisely the same number. Though, of course, it may be that Ferguson's words were actually intended for the referee, Martin Atkinson, more than anyone else.

Ferguson, as Mancini is coming to know, tends to plan these remarks in advance and this one seemed deliberately loaded when there is only one other referee, Phil Dowd, who has awarded more penalties than Atkinson this season. A classic Ferguson ploy? "Probably," Mancini concluded. "Fergie is clever like this."

Note the "Fergie". The only other manager who has referred to Ferguson like this in the past few years is Kenny Dalglish, someone else who refused to be cowed by the most successful manager in the business. The difference is Mancini knows how to get the better of his rival, starting off with the 6-1 thrashing at Old Trafford in October last year, moving on to the 1-0 win in April when United barely managed a shot at goal and, finally, that seminal afternoon at home to QPR in May, two goals in stoppage-time and all the associated glories of that last, football-bloody-hell kick of Sergio Agüero's right boot.

Ferguson has never really opened up about that afternoon, what it was like being seconds away from winning the league, how the news got to him and the awful emptiness it must have left. "It's gone, it goes away quickly," was about the sum total of it on this occasion. The previous time he was asked he restricted himself to saying there was only one way to put it out of his mind: "Red wine." Yet there was a comment earlier in the week that made it clear how, even if Liverpool are United's historic rivals, City is the fixture that matters these days. Three years ago Ferguson was talking about City being "a small club with a small mentality". Now he says ending their two-year unbeaten run at home would constitute "one of our best-ever results".

The team in red go into this match three points ahead of the one in blue but both of them should probably be grateful that everybody else in the top division look so bland. Nobody should be too surprised that the league has become a two-horse race but most people would have expected it to go that way in April or May, not November through to December, and it is certainly a strange set of events when Ferguson and Mancini are clearly dissatisfied with what they have seen so far.

Ferguson pointed out that United have conceded 10 goals from set-plays, grumpily adding: "Which is a lot." Earlier this week he described their defending as "Cartoon Cavalcade" and, unless it is another of his decoys, the game has come too quickly for Nemanja Vidic to provide the antidote. If Mancini noted United's vulnerabilities in the 4-3 win at Reading last weekend, there must be an outstanding chance he will play his best header of the ball: Edin Dzeko.

The problem is that Dzeko is a prolific substitute but too often a cumbersome starter. Mancini is frustrated, in fact, by all his front players. Of the four only Carlos Tevez has more goals than at this stage last season, seven compared with zero, and that is skewed by the fact he was on strike somewhere in Argentina a year ago. Agüero is down from 11 to five, Dzeko from 10 to six and Mario Balotelli seven to one. City had greedily accumulated 49 goals this time last year. This season they are on 27.

"Our season depends on our strikers," Mancini said. "We need to improve the output from our strikers. Our problem is our strikers. Usually when you have four strikers, two or three of them are not scoring but one is. At the moment we have four strikers who can't score."

He reinforced the point when informed that United have conceded 10 more goals in the league. "Yes, but they have also scored 10 more goals than us," he replied. It is actually nine but everyone understood the general idea and there was the clear sense, once again, that the Italian will probably always be aggrieved about the way the club, fresh from winning the title, lost out to United in the battle for Robin van Persie last summer.

"They were already a strong team and then they bought Van Persie and [Shinji] Kagawa. They put another 25 goals into the squad. We were in a difficult moment. We changed the CEO and the man who was in charge [of transfers] in that moment [Brian Marwood] … if you are not strong enough, you can have some problems in the transfer market. And, for us, the market was really difficult." City, he admitted, "don't have the same quality this season that we showed in the first 15 games of last season".

Of the two clubs City have certainly felt the more tense. None of Mancini's players would talk to the media, outside official obligations, after the defeat by Borussia Dortmund that confirmed City's position with the Champions League's wooden spoon, without a win and not even qualifying for the Europa League. Mancini's job has come under scrutiny again, much to the disappointment of the majority of supporters. Gary Neville, at a Barclays question-and-answer session in Manchester on Thursday, said there was "an inevitability that one day either Pep Guardiola or José Mourinho will be at City".

If there is a consolation, it is that City can now prioritise the league without the sapping effects of midweek European excursions. "I honestly think it is an advantage to City," Ferguson said. "The less games, the less chance of injuries. It gives them a full week to prepare for games now. But I think they would rather have European football. Any big team would want European football and that's the biggest disappointment for them."

This is one thing the two managers can agree upon. "I made some mistakes, the players made mistakes and we could have done better [with transfers] in the summer," Mancini said, "but this is in the past and we can do nothing about it now. All we can do is work hard to improve our performances."

Do City need to win the league to prevent the club's owner, Sheikh Mansour bin Zayed bin Sultan al-Nahyan, recruiting another manager? "I don't know. You need to ask him. I am happy with my job in two years here. When you build a new team sometimes you can have a difficult moment but this is normal."

Tongue in cheek, perhaps, but football, he appeared to be saying, was too impatient a business. "If I haven't made a mistake, Ferguson won his first [championship] trophy after seven years and his first Champions League after 14 years. I have another 12 years to win a Champions League."

First things first, there is the small matter of protecting that 37-match unbeaten league run at the ground Ferguson once called the Temple of Doom. "Two years," Ferguson said, nodding his head appreciatively. "It's a long time."