It was, according to Cesc Fabregas, the match that Arsenal had to win. Although, with seven minutes remaining on Sunday afternoon, it seemed like the match that Manchester United could not lose. How Arsenal came to beat the Premiership leaders in one of the season's greatest games was, the midfielder explained, his team's way of showing they will no longer be regarded as one of the League's soft touches.
The title race turned on the day that Fabregas claimed Arsenal got their attitude back.
The Spanish midfielder said the humiliation of defeat to Sheffield United on 30 December galvanised Arsenal's players, and the meeting they held together in the aftermath resolved that they would no longer leave themselves open to the criticism that, as the Sheffield player Phil Jagielka said at the time, they "behaved like babies".
That was a description that infuriated the Arsenal manager, Arsène Wenger, who believed that his team were kicked out of the match at Bramall Lane. For Fabregas and his team-mates it proved to be the moment that they arrested the slide. They have won all five of their games in the Premiership, FA Cup and Carling Cup since then and did so with 10 men against Blackburn and, in most of that game and on Sunday, without the suspended Gilberto Silva.
"We [the players] had a talk after Sheffield United that something had to change with our mentality and we had to be stronger in every part of our game," Fabregas said. "Since then we have been showing everyone we have changed, we have moved on. No one can stop us if we play like we are doing.
"We lost 1-0 at Sheffield United and there were a lot of things we had to improve and think about and that's what we did. Right now we feel good. We have to be consistent and we have to show everyone that we can beat Manchester United, Chelsea, Tottenham and Liverpool. We have drawn five games at the Emirates against [lesser sides] - I don't like to call them the small teams. It would be annoying for us if we don't beat them, but we have to keep this mentality going in the same positive way."
The reaction on Sunday from the Manchester United manager, Sir Alex Ferguson, was blunt - "I can't believe we've lost" - although it may be explained by an afternoon in which, despite his goal, Wayne Rooney looked less than comfortable switching between the left and right wings. Arsenal may have "resorted to long balls", in his words, but United looked uncomfortable dealing with them in the final 10 minutes.
The cynics might suggest that the ideal test for a resurgent Arsenal will present itself on Sunday when Bolton Wanderers, who beat them 3-1 in November and are a familiar problem side for Wenger's team, make their first visit to the Emirates Stadium, for an FA Cup fourth-round tie.
In wondering at the scale of United's collapse on Sunday, as they conceded twice in the final seven minutes, it was easy to gloss over the steps Arsenal have taken since Thierry Henry's return. Despite his being a scowling, gloomy presence among his team-mates for much of Sunday's match it is impossible to ignore the fact that Henry has scored in every one of the four games since his one-month rest. He does not look like the easiest team-mate to play alongside, but it is hard to argue with his record.
"He is unbelievable," Fabregas said. "We have been watching him for seven years and he has always been at the top. Every season he normally scores at least 24 goals, and that tells you a lot about him. This season we missed him because he is so important and he is so experienced.
"Last week against Blackburn he scored the second goal and we could be more relaxed. This time he scored with two minutes to go and it was the winner against United. It was a great cross from Emmanuel Eboué but he still had to put it in the net. That's why he is the best."
Fabregas insisted that he will not accept Arsenal are out of title race "until someone says it is over". On Sunday, that someone seemed to be tugging at Arsenal's sleeve until the last seven minutes.
But United are not the first to fall victim to Arsenal's late rallies - over the previous calendar year Arsenal had scored 10 goals in the last 10 minutes of games.
"This was the big day," Fabregas said. "If we drew or lost, then we could say goodbye to the Premiership. Now there is a small chance."