Everybody is offering their predicted formations and results for this game right now. Personally, since Manchester City are at home, very settled and have to win, I think their formation is relatively easy to predict. I expect it to be their usual 4-2-2-2 with Barry and Toure holding, Silva and Nasri on each wing but coming inside and Tevez and Aguero furthest forward. Generally, when playing together, Aguero pushes up onto the last man whereas Tevez will stay deeper between the opposition lines of midfield and attack. This causes a lot of problems as the defence must either step up toward Tevez, but leave themselves vulnerable to Aguero’s pace, or drop deep. This means they must either have their central midfielders move deep as well to cover Tevez but sacrifice some attacking threat to do so, or leave Tevez with a lot of space which is dangerous.
How United will deal with this threat is likely to be the key aspect of this game, especially as a win isn’t entirely necessary so blunting the City attack ought to be an attractive proposition. Ferguson’s tactics are often difficult to understand and his tactical nous has been questioned in the past. This isn’t to say he has no tactics however, far from it. The trouble is rather than making the expected changes of shape he often subtly adjusts his normal 4-4-2 in order to deal with different threats. He does this either by using different personnel such as Park, Valencia and Nani as well as the varied midfield duos available, thus offering different interpretations of the same roles, or by asking players such as Rooney to alter the role they play. As a result of this they can line up with the same team in successive games but with vastly different formations, as shown below.
Due to the fact United don’t have to win and are playing away, albeit within the same city, I would expect them to line up with something approaching the second variant shown above. Also, the majority of Manchester City’s defeats this season have been inflicted by the 3 man midfields of Bayern Munich, Sunderland, Swansea and Arsenal. The personnel is the interesting question. I wouldn’t really like to speculate who Ferguson will select, instead I’ll offer what I would do and explain why.
While my first choice would probably be to sacrifice Welbeck for an extra “true” midfielder and allow Rooney to move higher up the pitch I doubt Ferguson will do this so I will ignore it. The main area I think United ought to make a selection alteration is to utilise Phil Jones in the CM/DM role. This is because it solves their defensive dilemma regarding Tevez and Aguero. Jones will be comfortable sitting deep and tracking Tevez on his own, allowing his partner, most likely Scholes or Carrick, to move forward in possession and either sit deep alongside him when defending, in order to congest the midfield area that Nasri and Silva will also move into, or pressurise Toure and Barry higher up the pitch with Rooney. Of these options I would pick the former as neither Toure nor Barry offer much creativity and incisive passing from deep, hence the loan signing of Pizzaro as a regista (deep-lying playmaker).
Additionally with Jones in midfield Ferguson may feel more willing to field the less defensively reliable option of Nani on the left as he did against Everton. This would pit him against the less attacking Zabaleta (unless Richards is fit) and Nani offers greater variety in attack. If United don’t field Jones in midfield then I would be very surprised to see Nani, instead I expect they will defend deeper in two banks of 4, requiring the greater discipline of Valencia and Young. Also Ferguson obviously doesn't trust Nani against attacking fullbacks as he chose to use him on the left last week against Everton rather than up against Baines on the right.
These changes would mean United lined up as below and had clearly defined battles against the City attacking players with either Evans or Ferdinand as the spare man depending upon which side Aguero moves to.
There is a lot of room for this in Ferguson’s selection, hence I have offered my own ideas rather than a genuine prediction of his lineup. The less unexpected surprises may be to drop Welbeck and use an extra midfielder, to use Valencia, Smalling or Jones at Right Back if he is unsure of Rafael defensively (though he has started quite a few games recently) or to use the energy and discipline of Park either wide or in midfield in place of Welbeck.