The context of the match is critical for Sir Alex.
Manchester United used to start their season too slowly. Following Manchester City's new challenge a couple of seasons ago, Ferguson determined that United must start fast. They did last year, but City started even faster.
This season they are the two teams the others want to beat, having sewn up the Premier League last year. With both having personnel changes and new players to bed in, both will be disappointed so far.
Ironically, Mancini should be the more worried. Although both teams have lost two matches so far, City sit behind United in the EPL and bottom of their Group in the UEFA Champions League.
Furthermore, they have won only one of their last six and two of their last eight, against QPR and Fulham. Like United they are shipping goals, with City conceding in every match and United conceding first in six of theirs.
So both defences need sorting out.
United must do this for Sunday. You can't keep coming back from a goal down, even with Robin Van Persie in the team.
Newcastle United have two very dangerous strikers in Demba Ba and Papiss Cisse. Like the latter, Wayne Rooney hasn't hit the form of last season yet. Cisse has one and Rooney none in all competitions. Both stats are likely to change this weekend.
Once again (and this must be giving Sir Alex sleepless nights), injuries will dominate the thinking. After the horrendous and almost unprecedented injury crisis last season, especially with centre backs, he must have hoped for better luck this year.
In fact it has been almost as bad. Amazingly, Rio Ferdinand has been the fittest of the five at his manager's disposal. Vidic, Evans, Smalling and Jones have all been indisposed. In fact, the latter two have not played a single match yet.
At last, Sir Alex has realised that he needs to give his younger players a chance. Michael Keane and Scott Wootton both played competently in the Capitol One Cup against Newcastle; Wootton came on against Cluj. Ba and Cisse could give them nightmares.
Last season, United took only one point off Newcastle. A midweek away match at St James' Park was a 3-0 drubbing with Demba Ba scoring one of the goals of the season.
At Old Trafford, a disgraceful penalty decision stole a point, but United should have had it sewn up before then.
That was then and this is now. Alan Pardew has brought in a few more squad players. Sir Alex has signed a world-class striker and a European standard No.10.
The defence in general and Patrice Evra in particular are getting the blame for conceding, naturally. But United attacks from the back and defends from the front, so the whole team is to blame.
A key point which has been mentioned elsewhere is the vacuum that opens up in midfield when Scholes and Carrick play. In the second half against Spurs, everyone pushed forward and United were irresistible. Against Cluj the whole team pushed forward, and with 73 percent possession, United won easily.
The most extraordinary thing about that Cluj match was the "wingless wonders." For a team renowned for playing 4-4-2, this was a revelation. It was a clear demonstration that Sir Alex is moving towards a mobile, fluid, interchanging, fast, short-passing game like Barcelona.
It would have worked even better if Evra and Rafael had taken on their respective full-backs, but they seemed to be under orders.
Sir Alex is unlikely to repeat that formation on Sunday because it would signal that he would take a draw. Newcastle are a better team than Cluj. But counter-attacking is bread and butter to United, and with pace across the team, we may see a mix of the two.
So before considering the key battles between Newcastle and Manchester United, let's think about formations.