“We’ve been doing something for four and a half years. Players know exactly what to do and what my expectations are. I don’t think that changing the wheel, all in one day, is going to do anything really tactically great. What it will do is put confusion in the players’ brains, and once you do that, then you’re not going to get the best out of them.”

Nor will allowing them to spend too much time on social media.

When Australia beat Tunisia 1-0, Arnold gathered all of his players in a circle and told them to enjoy the moment – but as soon as they walked back into the sheds at the Al Janoub Stadium, where they’ll be back again to face Denmark, the moment was over. They’d won nothing, done nothing. Not yet.

If there was one thing Arnold learned from his campaign with the Olyroos at the Tokyo Olympics, it was the dangers of getting carried away. An upset win over Argentina by Australia’s under 23s had everyone beating their chests and tooting their own horns – but then they lost to Spain and Egypt, their medal hopes unravelled, and it was all for nothing.

“It’s too much celebration. And that celebration, I’m sorry, is social media,” he said.

“And they get on that until four or five in the morning, and watch all the great comments, and enjoy all that shite, if I can say that. It affects the players and affects the sleep patterns. If you’re up to five in the morning, looking at that, and looking at the good comments, and people backing you – the same people who are backing you are, the day after, the ones killing us.

“So just get rid of it. Don’t look at it.”

Arnold won’t enact a blanket ban on Twitter, Instagram and Facebook at the Socceroos’ Aspire Academy headquarters in Doha – it would be impossible to enforce anyway upon modern athletes – but he has warned his players not to go overboard.

Who needs the Screen Time app to police your iPhone usage when you’ve got your coach looking over your shoulder?

“It’s what I’ve learned over many years,” he said.

“It’s something that I’ve never looked [at] – I don’t do it, and I know I keep saying to you, and I hope finally you might be believing that I don’t read anything, but I know the effect it can have on people. It does have a huge effect on celebrities, sports stars ... if it affects your brain, it doesn’t matter how fit you are, technically how good you are, or how good the tactics are – they don’t take it in because they’re mentally not ready.

“I’m really glad I played in the days where there was no mobile telephones, no journos giving you ratings out of 10. It was a long time ago, but it’s a big thing. I think players these days are so mentally strong because of that, but at the end of the day, I have to get my wife off social media, I have to get my kids off social media, because it nearly kills them.”

Arnold has given his 26-man squad a clean bill of health – including Nathaniel Atkinson, who missed the Tunisia clash with an ankle injury, and Ajdin Hrustic, who came off the bench for his first World Cup minutes and is now in contention for a bigger role, but was in sneakers at training on Monday, restricted to “light duties”.

Mathew Leckie, who has logged more kilometres than any other player, was in the gym, given the night off running.

Arnold also has a fair amount of inside information on Denmark, from Socceroos like Maty Ryan and Joel King who play club football in the Danish Superliga, and assistant coach Andrew Clark, who works for FC Copenhagen.

“We’ve got players who play against them weekly and know them and are very confident against them,” Arnold said.

“Andrew Clark is obviously here for sports science, and I actually didn’t think the Danish club would release him for that reason, initially, but now it’s come to that, where it’s us against them, and Andrew Clark has a lot of detail on the Danish players that he’ll be able to give to us.

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“They’re a very good team, they’re ranked No.10 in the world for a reason.

“But I’ve seen we’ve gone up to 30 after the win against Tunisia. We respect them, but it’s all about us, it’s about getting our game plan right and making sure we make it very, very hard for the Danes.”

Before facing Tunisia, Arnold joked he hadn’t slept soundly in 12 years, so badly did he want to bring World Cup success to the Socceroos.

Now he has, and he still can’t get in eight decent hours of kip.

“I just want so much more,” he said.

“I can’t explain it, because it’s just such a strong passion I have for Australian football, and to see the celebrations ... I got sent a few videos from friends, but also random people, of pubs I’ve never heard of, or places I’ve never heard of, and people going crazy. That’s what I’m here for, just to put smiles on people’s faces.

“It’s been a fantastic journey, but as our team identity [says]: Many journeys, one jersey. The journey’s not finished yet.”