The Gunners just about deserved to win, although in truth they did not really test Edwin van der Sar until Aaron Ramsey scored his 56th minute winner.
Arsenal were on balance the better side, but they were still guilty of trying to pass it into the net on too many occasions. It they won this particular match, it is the same approach which has seen them fall short on all fronts this season and several before it.
They must not allow this win to convince them that a big reappraisal of their situation - from the football they play to the playing staff - is not needed in the summer.
Considering the history between these two sides and what was at stake, I thought the game was a bit of a disappointment.
United were poor, and their performance at the Emirates puts their much-lauded display at Schalke in their previous game into some kind of context.
They just never looked as though they were going to make a difference in this game. People at Schalke would have watched the game and been shown the way to try and beat United when they come to Old Trafford on Wednesday: stop Wayne Rooney playing.
Arsene Wenger did that by dispatching Alex Song to look after the England striker, who loves to drop deep and cause havoc in between defence and midfield. Ramsey, who greatly impressed in the absence of Cesc Fabregas, also did his fair share of helping out with the defence.
In the absence of Ryan Giggs, Paul Scholes and even Darren Fletcher, United's uneven midfield struggled to work out just how to find a way through with Rooney neutralised. It is so rare that you see a United team stumped as to how they plan to set about their opposition, but that is what happened at the Emirates on Sunday.
I still find it unlikely that United will let their lead slip from their grasp, though. Chelsea were very average against Tottenham on Saturday. They still lack a great deal of genuine creativity and Fernando Torres was not able to build on scoring his first Chelsea goal last week. Had it not been for them getting one goal which hadn't crossed the line and another that was offside then the result at the Emirates would not have mattered, United would have all but won the title.
At Old Trafford on Sunday United will be much more confident of hurting Chelsea on the counter-attack with their own crowd behind them and the Blues needing to win.
With United going to Blackburn and then hosting Blackpool on the final day they are almost certain not to drop any points, so Chelsea simply have to get their noses in front at the weekend or they can forget about the title.
However, I just cannot see United losing two big games on the bounce, especially at this stage of the season. In the years when they have not won the title it has never been because they have blown a lead.
Whenever Arsenal or Chelsea have won the Premier League, they have always been the best team from the outset. That is not the case this season, and now that United are in the box seat with so few games remaining you would have to say they should get over the line.
- Manchester United