I sensed the same belief and desire at Emirates Stadium on Sunday that we had at Highbury when I won Premier League titles with Arsenal back in the day.
Right from the start, Arsenal's energy was just incredible and they were absolutely relentless in the way they kept coming forward, looking for the victory.
The home crowd played a huge part in that, the same way they did when they were driving us forward when we won titles under Arsene Wenger.
The chants of 'Arsenal, Arsenal, Arsenal' when they were chasing a late winner took me right back to those days, and I found it extremely powerful.
As a player, you feed off the fans as much as they respond to what is happening on the pitch, so of course they made a difference against United.
Even when things went wrong, the fans knew this Arsenal side was good enough to win the game, so they were not worried about what United might do.
They know what they are watching and, just like they used to watch us rock up and all think 'right, let's win this as quick as we can' when I played under Wenger, they know now they have got another team that can beat anyone.
That's their outlook in every game, home or away. Against United, whether they were 1-0 down or when it was 2-2 in the last 10 minutes, they wanted the victory and kept urging the players forward because they thought they could get it.
The team responded to that - they didn't panic, they kept playing, and they found a way to win.
Wins like this one will change people's minds
There are really only two possible endings to this Premier League season now - either Arsenal or Manchester City will win the title.
The Gunners are five points ahead with a game in hand, which is a big cushion, but you still wonder 'is it enough?', and not only because they still have to play City twice.
We are waiting to see if City will wake up and regain their fire, while at the moment Arsenal are flying and in such fantastic form.
The uncertainty is not from the way the Gunners are playing, it's because this team has never won the Premier League before - in contrast to a City side going for their fifth title in six seasons and, along with Liverpool, have set standards we have never seen before.
Arsenal are at a different stage, where they are reaching upwards and still developing. Even now, with the lead they have got, no-one is really prepared to say they will win the league with the same conviction they would if City were in their position now.
It is results like this victory over an in-form United team that will change people's minds, and the way they got it was a statement too - there is no doubt that Arsenal really caught the eye and their performance will resonate throughout the game, including everyone at Etihad Stadium.
Arsenal can show their teeth in the cup
Teams show how good they are by winning trophies, not by sending out messages, but it is games like Sunday where you demonstrate your character and personality, and show your teeth to your rivals too.
When we won the Premier League title in 1997-98, which was right at the beginning of the Wenger years, we were building our reputation in the same way as Arteta's side are now - and we won 10 games on the bounce between March and May.
We knew we had to keep winning, otherwise we might open the door even slightly for United, who we overhauled in the final few months of the season.
Arsenal have not won anything yet, and Friday's FA Cup tie at City is when we are really going to have to see their teeth.
That is a game that the Gunners are not expected to win, even though they are top of the league and, on current form, look like they are a different class.
It's City who still go into that game as favourites, because they are established as one of the best teams on the planet.
If Arsenal can go to Etihad Stadium and win, just think about what that would do for the group. It's the perfect game for them to play next after their wins over Tottenham and United, and I am confident they will rise to the challenge.
Martin Keown was speaking to BBC Sport's Chris Bevan.
