Sunday's win at Arsenal was another unbelievable result for Manchester United and I was hugely impressed with the way they got it. Just like in last weekend's Manchester derby, ultimately this victory came down to the fact that their big players are turning up for them now.

For example, when you go down the spine of the United team at Emirates Stadium, they all looked like the players we know they are. Harry Maguire was brilliant at the back, then you had Casemiro in the middle of the park, using all his experience. Bruno Fernandes, back in his favourite position as a number 10, was outstanding, and up front Bryan Mbeumo was a goal threat, but also able to hold the ball up, and scared people with his pace and energy.

United scored two brilliant goals, but their victory did not rely on outstanding individual performances or moments. Instead, the whole team played their part in this win, and manager Michael Carrick deserves credit for finding a way of making that happen.

People will naturally compare this United performance to what we saw from the same players under Ruben Amorim at the end of his time in charge, and it felt like we were watching a different team. There is an element of motivation and communication from Carrick that will have helped his players, of course, but the key for me was that they all looked really comfortable with the way the team was set up.

As I explained on Match of the Day, they look happier - their body language is good and they all want the ball - they all trust each other with the ball too, and there is visibly much more confidence. I can understand why. It sounds quite simplistic but something that is not always talked about as much as it should be after a display and result like this, is the difference it makes when you put players in a formation that suits them, which they understand.

Here it was a 4-2-3-1 or 4-4-1-1 shape with Fernandes as a 10 behind Mbeumo. Amad Diallo and Patrick Dorgu were both willing to get back, because they have played as wing-backs and have done that defensive role before. That meant United were sometimes a back six when they had to be - but even then Diallo and Dorgu still knew they were wingers when their team had the ball.

Everyone knew their jobs, with Fernandes dropping in and helping Kobbie Mainoo and Casemiro, who were screening the back four nicely. On a basic level, United's shape and what their players were asked to do, meant they defended in numbers and then, when they got the chance - bang, they flew forward. With the pace they've got, they were so dangerous.

To win at the Emirates, both sides of your game have to be more than just good - you have to be excellent with the ball and without it. You have to be really good defensively - organised and drilled - so everyone, collectively, knows when to sit in and focus just on stopping Arsenal from playing. But, also, you have to be ready when you get your chance on the ball and get forward too - whether it be on a counter or by building an attack with sustained possession - and then when you get up the pitch you have got to carry a threat.

United achieved all of this, right from the start of the game. They caused problems for Arsenal because they didn't just stay deep - they tried to have a press, which is brave at the Emirates, but it worked. Combined with Arsenal being nervous or being too casual, it created some openings for United, which they almost capitalised on.

Arsenal had actually started the game really confidently in many ways, and dominated possession and territory. When they went 1-0 up I thought that would give them complete control but it actually shifted United into gear. Suddenly they played with a bit more freedom and took a few more risks - and, with the help of Arsenal, they got back into the game.

From the moment Mbeumo equalised, United looked really confident. They went in at half-time with their belief enhanced because of the 1-1 scoreline, then Dorgu goes and scores a wonder goal after the break and all of a sudden they have got something to hang on to, and they are able to play on the counter a bit more.

At that point, I think Arsenal helped them again, by making four substitutes at once so soon after going behind, which struck me as a bit of a panic move by Mikel Arteta. The home fans wanted a change because they wanted some fresh impetus to turn the game around, but among the players who came off was Martin Odegaard, who was looking quite sharp, and Gabriel Jesus, who had done some really good things.

I felt making all those substitutions at once meant Arsenal lost some of their rhythm and momentum. It's a risk that all those who come on at the same time will have an impact. Arteta might feel it was one worth taking - one of his subs, Mikel Merino, did equalise from a corner - but at that point, United were still playing pretty well, and we know how good Arsenal always are at set-pieces.

At 2-2, with six minutes of the 90 to go, you think a point for both teams is not a bad result but United's belief was still there in abundance, and so was their quality on the break. Matheus Cunha's late goal to win the game was absolutely phenomenal, and was a reward for United's approach. They were not just there to contain Arsenal, and rattled them.

Even when they were 1-0 up against United, I was saying I'd never seen this Arsenal team make so many mistakes. Their lack of composure was unexpected because even in games like this, where they are maybe not free-flowing in attack, they still usually look in control. Here, that control was missing.

I would put some of that down to the pressure they are feeling in trying to win the title, because I've seen myself how maintaining your composure is really difficult for even the best players when the rewards are so high. I only really had one chance of winning the title when I was at Liverpool, in the 2001-02 season, and you could feel each game becoming bigger and bigger for everyone, the closer we got to the finish line. We had never really dealt with that kind of pressure before, and we struggled to cope and finished runners-up, seven points behind Arsenal, in the end.

That can happen to any team on a given day, especially at home with the expectation around Arsenal at the moment because of their record at the Emirates. The problem is if it happens repeatedly. Sunday's defeat has become a pivotal point in their season in many ways because we are all wondering if the issues that cost them against United will be compounded in the next game - or if this setback will be the jolt they need.

Arsenal have only taken two points from their past three games but are still four points clear at the top and we are nearly in February. They would definitely have taken that at the start of the season. They have also got some wonderful players, they are a powerful, physical side with so much strength in depth, and also have far more experience of this situation now.

That's why my belief is that we will see a positive reaction this time. Yes, United showed Arsenal are fallible and the best defence in the Premier League can make mistakes and give you chances. But let's put it in perspective, this was their first home defeat of the season. This was the first time I've seen them look vulnerable and that doesn't mean this is going to set the tone for the rest of the campaign, or that they will crumble from here.

That's still the question that will be asked of them in the media this week. Everyone is going to say, 'are they going to bottle it?'. But I don't think they will. They just needed a kick up the backside, and they certainly got one of those from United.

Danny Murphy was speaking to BBC Sport's Chris Bevan.