When I read back the notes I’d made about Arsenal during Sunday’s win over Manchester United, it was like a checklist of what it takes to be champions.

Mikel Arteta’s side had the mindset that meant they were able to handle the occasion, take control of the game and then see it out with the kind of defensive discipline and determination that has enabled them to keep 18 clean sheets in the Premier League this season.

When I was a Gunners player, winning at Old Trafford usually meant we also won the title too.

We will have to wait and see whether that is the case this year but, whatever happens now, Arsenal have shown fantastic mental resolve to get this far and overcome the obstacles they fell at last time.

They have won 15 of their past 17 Premier League games to make it as difficult as possible for Manchester City to defend their crown, going into the final week of the season.

The pressure was on the Gunners against United, and you could feel that tension in their performance. I think the history of this fixture was a big part of that, because there have been some huge games between these two teams down the years - I know, because I played in a few of them.

It all meant Arsenal were not at their best but sometimes when you are in a title race, you just have get through days like that and grind out the result, and they were so professional in the way they went about it.

I thought they were immense at the back, especially the two centre-halves, Gabriel and William Saliba, who were outstanding again.

Arsenal’s defensive improvement this season has helped them go the distance in the title race, and it was the platform for their win over United too.

There were times during the game where all 10 of their outfield players were behind the ball around the edge of their own area. Everyone was in position, they were dogged and resolute and it was like they put up a shield and were saying to United ‘can you get past us?’

United couldn’t get through which meant that, even when they were seeing a lot of the ball, they ended up getting frustrated and shooting from distance when they probably should have tried to play an extra pass.

Arsenal have gone on the attack in most of their games this season but we have also seen them play this way before – it was the same when they drew with Manchester City at the end of March. Their whole team had the same mindset, or shared defensive brain, against United and at the heart of it were Gabriel and Saliba.

They have played together in 33 of Arsenal’s 37 league games this season and their partnership on Sunday was like the opposite extreme of Jonny Evans and Casemiro, who are United’s latest pairing at the back. Casemiro is not a specialist centre-half and it really showed.

Gabriel is a very physical player who is able to swat attackers away, while Saliba’s style is more silky and smooth.

They are different types of defenders but they get in good positions and make the right decisions, and it is the way they work together and cover each other that makes their partnership so special.

It obviously helps they clearly enjoy playing alongside each other but, whatever the situation was against United, one of them would always see the danger and deal with it.

There so many things they did that impressed me but Saliba’s challenge on Alejandro Garnacho really stood out. It was the perfect example of how to deal with a forward running at you inside the area in a one-on-one situation.

Saliba stayed light on his feet and did not overreact or dive in too quickly. He created a barrier and then he put a foot in – his left foot, which is not his strongest – to make the challenge with absolutely perfect timing.

He made it look very easy, but then that is what great players do, and he is on the way to becoming one of them.

The 23-year-old France international has made the shortlist for the Premier League young player of the year but, along with Gabriel, I actually felt he should be in the mix for the main award. Both of them have been that good, all season.

Martin Keown was speaking to BBC Sport's Chris Bevan.