When I saw Gareth Southgate's team and system - with four at the back - before kick-off, I thought that we would be on the front foot and try to go at Iran, and that is exactly what we did, right from the start.

Now we have to keep doing that. Bigger tests await and I know we can't be as attack-minded in every game if we go deep into this tournament, but it's important we stick with that approach against our other opponents in Group B.

I've been in the situation as a player with England when people are saying that some games will be easy and you should win easily, and it's not nice.

But from what I saw in their game later on Monday, nothing would worry me from Wales or the United States, who we play on Friday. In fact, I'd be rubbing my hands together about facing them.

The system got the best out of every England player

There was a lot of debate before this tournament started about whether Southgate would go with five or four at the back, and whether he needed to be less cautious in Qatar.

It is not just your formation which decides how attacking you are, but England's 4-3-3 shape against Iran certainly played to their strengths going forward, and I actually felt like it got the best out of every player.

It gives us an extra man in midfield and that allowed Jude Bellingham to make those runs he did against Iran, and use his intelligence to get forward at the right time, like he did for the first goal.

Playing as one of two midfielders in a 5-2-3 shape makes it more difficult for him to do that, but against Iran he had more licence to roam - and it was exactly what we needed against a team sitting deep and defending in numbers.

Bellingham was amazing, as were Bukayo Saka and Raheem Sterling - though everyone else also adapted so well to the system too, including our centre-halves.

It was a big call by Southgate to pick Harry Maguire, who has hardly played for Manchester United this season, but his performance justified that loyalty.

I said in the studio at the start of the game that Maguire needed a few touches of the ball early on just to get the feel of things again, and England gave him that in the first five minutes.

Maguire and John Stones were not afraid to drive forward from the back and make that pass through to the forwards, which we needed when we were trying to make the breakthrough.

Iran were set up to frustrate us, but we stretched the play by sending our full-backs high up the pitch and they put some great crosses in, including the ball by Luke Shaw for the first goal.

I can understand why Southgate was disappointed by the goals we conceded at the end of the game, but 95% of that performance - from everyone - was brilliant. If that doesn't give us belief, nothing will.

Kane's wait for a goal won't last long

The manager deserves credit too, of course. As well as picking Maguire, sticking with Sterling was another big call Southgate got right.

Everything worked, including the changes he made during the game that saw Marcus Rashford and Jack Grealish come off the bench and score.

That is some heavy artillery to bring on if we need it, and it's great for them both to get a goal to give them more confidence.

The only person who might not be happy is captain Harry Kane, after failing to get on the scoresheet himself.

I was laughing with Gary Lineker after the game about how devastated we would both be, as fellow strikers, if that had happened to us when we were going for a Golden Boot.

Being serious, though, Kane still played very well. He is going to score soon, so his wait for a first goal at this World Cup won't last for long.

VAR the only cause for concern

My only slight concern after watching England had nothing to do with their display - it was the part the video assistant referee played in their game.

An Iran defender bear hugged Maguire to bring him down at a corner but nothing was given, which was just pathetic when you consider that Stones conceded a stoppage-time penalty for doing far less.

It didn't matter because we were so far ahead at the time, but imagine if we were 2-1 up and on the wrong end of a decision like that?

We've seen goals ruled out in other games for extremely tight offsides too - someone's toe or shoulder being the wrong side of the line - which I never like to see, and I just hope VAR does not get too involved in this World Cup because we will enjoy the football more without it interfering.

Alan Shearer was speaking to Chris Bevan in Doha.