An enraged Andoni Iraola said he will tell his players to go down in the area in future after Liverpool were not awarded a penalty in their defeat by Arsenal.

Liverpool’s head coach was left incredulous that Stuart Attwell, the VAR, did not intervene in the first half when Jurrien Timber grabbed Alexander Isak’s shirt as he tried to get his head to a cross.

Isak stayed on his feet as the ball whistled beyond him after his momentum was checked and Liverpool’s complaints were waved away.

It was a huge moment in a hard-fought game that Arsenal edged thanks to Kai Havertz’s 16th-minute goal, one that led to huge debate on the field and in the TV studio. Jamie Carragher simply said on Sky Sports: “VAR, do your job.”

Iraola went into significant detail afterwards. This is the kind of situation in which Ref Pro may end up issuing a retrospective apology, though the indications from Stockley Park are that they questioned whether there was enough contact from Timber to take Isak down.

But Iraola said: “It’s a shame you have to ask me this question, but honestly, yes, we have to tell them: Go down, because we are not going to call it otherwise. And then the referees complain why they go down, [but it’s] because if you don’t go down, you don’t call it.

“Then it’s like, you have [players] all the time going down. But I think Alex is honest. He tries to go for the ball. Everyone can see live straight away, there is a clear, clear pull. And even Cody [Gakpo, when he was pulled] in the second one. But I understand the explanation that they give in the second one.

“There are two situations, and they are a little bit related. I think the Isak one is a clear penalty. He’s [Isa] going to head the ball in front of the goal. They grab him where everyone sees the shirt [tug]. You don’t need a lot, just to avoid Alex, because the ball just goes in front of him.

“I don’t see the reason why. Probably because he doesn’t dive or he doesn’t go to the floor. It shouldn’t be a reason not to concede a penalty. And then after the Gakpo one, I think it’s a sustained holding.”

Asked by Sky Sports whether he would give Isak clear instructions to go down in the area when feeling contact, Iraola replied: “Yes, definitely.”

Iraola’s view was backed up by Virgil van Dijk, the Liverpool captain, who questioned why Isak should have to go down to be awarded a penalty when there is VAR available.

Van Dijk said: “I think it was a clear penalty. I’ve seen it back and I’ve seen it being given. Today it wasn’t meant to be.

“We have 50 cameras. Why does he have to complain when there are so many cameras? Everyone has seen it. In the end it wasn’t given and we lose the game unfortunately, so well done to Arsenal.”

Tempers frayed in the second half, as Liverpool tried to find a way back into the game. Noni Madueke escaped a second yellow card after pushing his head into Alexis Mac Allister’s face during a confrontation. The Argentine went down, but he was booked for starting the melee.

Words were exchanged in the tunnel after the game, as Van Dijk told Madueke he should have been sent off but the England international fired back and said that Mac Allister had been trying to get him into trouble. Mikel Arteta, Arsenal’s manager, had not seen any of these incidents.

Havertz, Arsenal’s scorer, was overjoyed to have had the decisive impact and he paid tribute to Declan Rice, who had provided the outstanding assist.

Havertz said: “This means a lot to the whole football club and it’s been 14 years [since Arsenal won at Anfield], that is a crazy stat and I think that we are all happy that we gave it to them today.

“I think we all know what this stadium is about and what the fans are about. Liverpool have big players and they can show their quality. We knew that this was coming for us and we all stuck together and defended together. 90% of the goal belongs to Declan Rice.”