Let the mind games begin. So Sir Alex Ferguson thought at his pre-match press conference before Manchester United's final Champions League group stage match against Cluj on Wednesday night, a dead rubber for his team given that they had already secured qualification for the knock-out stages.

"There's nothing better than big European nights," he mused. "Every manager wants to do well in Europe - I do, anyway."

The English press pack are all too keen to load Ferguson's words with meaning. Too much is often read into them. But there was nothing abstract or indirect about this comment.

Ferguson had been asked for his opinion on Manchester City's failure to progress beyond the Champions League group stage for a second successive season. It was taken as Ferguson ever so slightly needling Roberto Mancini ahead of Sunday's Manchester derby at the Etihad Stadium.

The relationship between the pair has, for the most part, been one of mutual respect over the last three years or so. Tempers may have flared in the 76th minute of their last encounter in April with Ferguson lashing out at Mancini after Nigel de Jong put in an ugly challenge on Danny Welbeck -- a lipreader claiming he said: "I've [expletive] had enough of this" -- but both insisted it was all only in the heat of battle.

"I think that once the game is over you have to accept that the other team are sharing the same emotions and desires and expectations as yourself," Ferguson said. "If you lose then you have to show you are capable of forgetting what has happened out on the field by sharing a glass of wine and a chat."

That doesn't mean they're not always seeking out an edge and that their relationship occasionally gets caught on it. The reverse psychology employed by Mancini is seen for what it is by Ferguson: nothing more than smoke and mirrors. "We're favorites every week according to him," he scoffed. "Does he not realize he's got a decent team himself?"

That Mancini also chose, after City lost 4-2 to Aston Villa in extra-time of a League Cup tie in late September, to make the insinuation that Ferguson and United receive preferential treatment left many observers under the impression that he had been unwise to pick a fight unprovoked.

"Every time I say something, they come," Mancini argued. "After, when they go to Old Trafford, they never say anything. When other managers [at Old Trafford] talk against the referee, they always stay on the bench and say nothing."

Mancini was probably trying to deflect attention away from another indifferent performance following the draws with Stoke and Arsenal and the defeat to Real Madrid that preceded it.

If not, however, then it was curious that Ferguson had got under his skin. Because, although Mancini has lost five and drawn one of his nine encounters with United since he arrived at the Etihad in the winter of 2009, it might also be said that the four Manchester derbies he has won were the most important of recent years.

He tasted victory in his first one, a League Cup first leg in spring 2010, which, even if City lost the second leg and went out, did lend Mancini credibility and went some way to justifying the club's decision to bring him in at the expense of predecessor Mark Hughes. He then came out on top the following year in an FA Cup semi-final as City went on to lift their first major trophy for 35 years. And as for last season, he masterminded a historic 6-1 win at Old Trafford, the worst home defeat United have suffered since 1955, and followed it up by prevailing 1-0 in a title decider, a match Ferguson described beforehand as "the derby of all derbies."

This Sunday's perhaps isn't a must-win for Mancini, but it's also important that City don't lose. To do so, and incur their first Premier League defeat of the season to their biggest rivals, would leave them deflated and six points off the pace heading into the congested Christmas period.

For that to come so soon after another dispiriting showing in Europe, when City, admittedly already out of the Champions League, succumbed to a second string Borussia Dortmund side and didn't even get into the Europa League -- finishing bottom of their group with the lowest points total ever recorded by an English team in the competition's modern format -- would bring severe scrutiny.

Ferguson has his worries too, though, particularly at the back. United have conceded 21 goals in the Premier League this season, only one fewer than they did throughout the entire 2007-08 campaign. "I can't remember us losing so many goals before Christmas. I must say that," Ferguson admitted. "So it is a concern, there's no question about that. When you look at the side City could put out, with Balotelli, Dzeko... all really tall players, it's going to be a big challenge for us on Sunday."

Writing in his program notes ahead of the Cluj match, it was clear Ferguson's focus is already on the derby.

"We need to come out unscathed," he explained. "With so much at stake I wonder if there will be a bit of caution from both clubs. Mancini and I will both have to think deeply about our selection and tactics and there may well be an element of playing safe. But don't count on it because it's a derby match when anything can happen and often does.

"The passion of the fans can easily spill over so that tactics go out of the window as emotions take over. We could be in for a master class of attacking football from both teams - in which case, hold on to your hats and enjoy."