The result might not have been as controversial or free-flowing as their 3-2 defeat of Chelsea was last weekend, but the win was no doubt still a confidence-boosting result for the Red Devils and their supports alike.
Sir Alex Ferguson's men were simply too good for their North London rivals on the day, and will take plenty away from the 2-1 win.
Read on to see six things we learned from United's victory over the Gunners in the English Premier League this weekend.
It seems like we're saying this every week, but Robin van Persie is good. I'd even go as far to say that he is the best thing to happen to Manchester United in a long time.
Really, Very, Perfect.
The Dutch international found the back of the net again for his new club when they needed it most—hammering home the first goal of the match in just the opening two minutes. What's more, he did it first-time and on his wrong foot.
He would prove to be a nightmare for his former teammates right throughout the match, forcing Vito Mannone to make several strong saves to prevent the Red Devils from truly blowing out the scoreline.
We all knew Van Persie was going to be big for United in both the English Premier League and UEFA Champions League this year—we just didn't know how big.
Perhaps we are starting to get an answer.
Antonio Valencia is one of the top wingers in the Premier League at the moment—whipping in devastating crosses to Rooney and Van Persie, and sparking the Red Devils' attack every time he touches the football.
But perhaps his biggest asset is his pace—a devastating turn of foot that leaves his opponents for dead out on the right flank of the field.
He made Andre Santos look like a fool on more than one occasion in this one (a feat that perhaps isn't that hard to do) and created plenty of good attacking chances for United down the right hand side simply because of his pace.
The imminent return of Shinji Kagawa and the strength of the Rooney-Van Persie combination will lead United through the middle more often than not this year—which is fine, as long as they don't forget the world-class wingers they have in their side.
Valencia's pace has already been a huge asset this season for United, and can continue to be throughout the year if provided the opportunities.
One reason why Manchester United fans seem so willing to let Nani go over the winter transfer window is that they assume they have another world-class international winger present on the left flank in Ashley Young.
The England star has been strong for United and is good with the ball at his feet. As a result, he was the logical started on the left if Nani ever left Old Trafford.
But after watching him against Arsenal, you wonder whether United really want to put all their eggs in one basket with Young on the left wing.
He was solid, and didn't in any way throw the game away for United, but he did fail to inject the pace, skill and attacking presence to be effective for the Red Devils. Maybe if so much of his time wasn't spend trying to win a foul, then he might have had more of an opportunity to do so.
Just a thought, I guess.
His performance could just be a one-off here, but if Young isn't going to deliver the same potency that Valencia can and does on the right wing on a regular basis, then United need to seriously consider whether they want to put all their trust in Young this season and leave Nani out of the fray all together.
Prior to the game, many wondered whether it would be Tom Cleverley or Paul Scholes that started alongside Michael Carrick in the middle of the pitch.
Big game, big expectations—the experience of Scholes wouldn't have been out of place, but in the end, Cleverley got the nod ahead of the veteran midfielder, and proved to many why Sir Alex Ferguson opted to include him in the first place.
He was strong in attack—sparking chances and moving the ball well across the pitch—and, for the most part, contained a strong midfield featuring the likes of Santi Cazorla, Jack Wilshere, Lukas Podolski and Mikel Arteta.
Cleverley wasn't perfect (hence his substitution), and is still learning his trade in the middle, but he is no doubt the real deal in central midfield for United this year, and for mine, their best option to play alongside Michael Carrick on a regular basis.
Is this the changing of the guard at Old Trafford?
After watching the Spanish international and his inconsistencies last week against Chelsea, I stated in my game review that I wasn't sure if David de Gea was good enough and consistent enough to get the start in big games for United this year.
David, I owe you an apology.
The shot-stopper was essentially flawless for United in this one—making big saves when his side needed to and read the game well also, an aspect in which he is perhaps known to have moments of failure.
He was beaten in the end by Santi Cazorla, but to keep Arsenal at bay for all but 90 minutes is no doubt a very commendable effort.
Away to Chelsea and home to Arsenal in the space of a week is a big task for a player still so young, but De Gea has handled himself well and deserves credit for rising to the occasion in two very big matches.
My apologies to De Gea—just don't screw up next week and make me look dumb.
It might not have seemed like the most convincing performance from the Red Devils today, and well, that's probably because it wasn't.
They were relatively poor in their finishing and gave the ball away far too easily coming out of defense. You wonder—had they played like they did today when they met Chelsea, the result could have been an entirely different one for both sides.
But at the end of the day, three points is three points, and United did the job over Arsenal. It wasn't pretty, but getting the job done is all Sir Alex Ferguson would have asked for, and expected, at the start of this must-win match for both teams.
The veteran manager simply knows how to get a win when his side must win and knows how to walk away from big matches with three points and not one, or none.
Given how close the title race was last season and the way United have played over the past week, a bit could well be the difference between success and failure this year.
If it is indeed glory and not heartbreak this year for United, much of the credit should fall on Sir Alex Ferguson, who simply knew how to get his team over the line.
He's just that good at getting the job done.
What did you make of Manchester United's win over Arsenal?
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