After that 1-0 defeat at the Emirates it seemed that Manchester United were shoo-ins for an unprecedented 20th English league crown as it put them eight points clear at the top of the table.
The prospect of City's players having to give United the most expensive guard of honour in history at the Etihad Stadium on April 30 was a very real one.
After United were held to a humdinger of a 4-4 draw by Everton at Old Trafford on Sunday, followed up by a 2-0 win for City at Molineux which saw their hosts relegated, beleaguered Wolves boss Terry Connor was probably not the only one moved to tears.
Sunday's results have now swung things back in City's favour. They are now three points behind United with three matches remaining, and they have a superior goal difference by six. Barring an extraordinary glut of goals in United's final games, City will be champions if they pick out all of the final nine points available to them this season.
Now that derby clash at City's place next Monday is primed to be one of the biggest matches the Premier League has seen for years. While this weekend sees a handful of dead rubbers like Everton v Fulham, Swansea v Wolves and Norwich v Liverpool, we have to wait a full week to see if City can repeat their six-goal exploits of the reverse fixture or if United can finally put this championship battle to bed.
As United striker Michael Owen put it on Twitter this morning, taking a break from his usual posts about horses and his favourite chocolate bars (FYI: 1. Picnic, 2. Topic, 3. Star Bar) to say: "This is going to be the longest week ever leading up to Monday's game with City."
Alex Ferguson and Roberto Mancini have interpreted the circumstances they find themselves in slightly differently. United boss Ferguson believes that "we've given (Manchester City) the initiative, there is no doubt about that", while City's Mancini said "I think they have a bigger chance, more than us in this moment".
One thing that it was not difficult to interpret was United's defensive failings against Everton. It was the first time in more than 53 years that Manchester United scored four or more in a top flight match at Old Trafford and failed to win.
Whilst the Toffees were excellent in both their determination and enterprise — and David Moyes left a useful calling card at Old Trafford for whenever the vacancy there opens up — United were at times lethargic and unorganised at the back.
After going two goals to the good — first at 3-1 and then 4-2 — United looked as though they thought the game was won; but somehow Everton were allowed a way back into the game. When Tony Hibbert claims two assists against you, questions must be asked.
"There were defensive lapses," said Ferguson. "Their goals were really soft. It was a real shock for us to defend like that.
"It was a travesty of a result in some ways but we made it difficult for ourselves and if you look at our history we keep doing that. We've thrown a game away that we should be coasting."
The draw represented the seventh time that United have conceded three or more goals this season in all competitions. Before this game there was the 3-2 loss at home to Athletic Bilbao, the 3-3 draw at Chelsea, the 3-0 defeat at Newcastle which came right after the 3-2 home loss to Blackburn, the aforementioned 6-1 drubbing but City and the 3-3 draw at home to Basel.
It can surely be no coincidence that United's best centre-back and club captain Nemanja Vidic was absent from every single one of those matches.
The big Serbian only played 10 games for United in the first half of the season before his campaign was ended with a knee injury in December's 2-1 defeat at Basel, having also missed two months of action between August and October with a hamstring problem.
Regarding United's recent record of shipping three or more goals, they did so three times in each of the three seasons before this one, and not at all in the two before that, which takes us back to 2006-07, Vidic's first full season at the club.
True, United have seen the transition from the retired Edwin van der Sar to David de Gea in goal this term, and Jonny Evans has performed better than many expected upon stepping into the breach alongside Rio Ferdinand, but Vidic's absence for most of season has been telling and may ultimately prove the difference in the title race this season.
Just as City fans can point to Carlos Tevez's exile for much of the campaign, so United supporters can only wonder whether they might already be celebrating another title had Vidic been fit.
Next Monday's derby is being billed as a title decider, when the efforts of an entire season are virtually boiled down to one 90-minute match. If United's defence is once again exposed and exploited as it was so ruthlessly by City at Old Trafford, it will only lend credence to the idea that their title hopes were scuppered when Vidic was stretchered off the field in Switzerland four months ago.
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QUOTE OF THE DAY: "Once I was on my feet for the first time I felt like a toddler again - like my three-year-old son Joshua. I could barely put one foot in front of the other and had to be carried back to my bed - but it was a start. A few months ago I would think nothing of running miles, but now I'm tired after a 20-minute walk around the block. But now I'm making progress. It's too early to say whether I'll play football professionally again but I have great faith in God and I have hope, so who knows? If I can come back from the dead then perhaps I can achieve anything." — Bolton Wanderers midfielder Fabrice Muamba begins the long road to recovery after suffering a cardiac arrest at White Hart Lane little more than a month ago.
FOREIGN VIEW: There were extraordinary scenes in Italy on Sunday when hardcore 'ultra' fans of relegation-threatened Genoa forced their team's match against Siena to be suspended after the home side went 4-0 down. Smoke bombs were thrown on to the pitch and some climbed over the Perspex barriers on to the field too. Fans demanded the players remove their shirts as they were not fit to wear them, and amazingly some complied. The match was eventually restarted, with Siena winning 4-1.
COMING UP: You can watch every goal from the weekend's Premier League matches online right now, as well as see extended highlights of each game and our pick of the top five goals.
Paul Parker will be offering his verdict on the weekend's action, while we will be selecting our Team of the Week.
This evening you can follow live coverage of the Championship clash between Leicester City and West Ham United as the Hammers hope to close the gap on second-placed Southampton.
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