Leckie, along with skipper Maty Ryan, was making his ninth World Cup appearance for Australia, tying the record held by Mark Bresciano and Tim Cahill, who watched on from the stands alongside Football Australia chief James Johnson. None of them will ever forget this day, which will turbocharge the sport back home with nitrous oxide – or the final half-hour they suffered through, or the six agonising minutes of stoppage time at the end.

At the final whistle, utter disbelief from them all. Yet it was belief that got them here in the first place.

Once again, Arnold stuck with almost exactly the same starting team for the third match in a row. The only difference was at right-back, where defensively minded Milos Degenek and his “lion mentality” was given the nod ahead of Fran Karacic after his nervy start against Tunisia – while creative midfielder Ajdin Hrustic, back from his ankle injury, remained on the bench.

The Danes, meanwhile, made three changes from the side that lost 2-1 to France, bringing in Espanyol striker Martin Braithwaite, Brentford midfielder Mathias Jensen and Club Brugge winger Andreas Skov Olsen.

The biggest question was whether the Socceroos had the physical reserves to repeat that Tunisian performance against a superior opposition, with the Danes ranked No.10 in the world by FIFA, considered by many one of the dark horses to take out the tournament, and under pressure to perform given their sluggish start in Qatar.

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The answer proved an emphatic yes, but the early signs weren’t good. Australia spent the opening half-hour under siege, with an early yellow card to left-back Aziz Behich amplifying their nervous start. Both teams were making needless turnovers – but then Denmark stopped, started stroking the ball around nicely, stretching the Socceroos’ defence with their superior quality and peppering the goal, forcing them to hold on for dear life.

It took utter desperation to keep the Danish wolves at bay – through a block from Degenek to deny Jesper Lindstrom, a save from Ryan to bat away Jensen’s angled effort, while an overblown shot from Skov Olsen left them on the hook, five minutes before an incision down Australia’s right-hand side almost found its way through a sea of legs, with McGree clearing the danger.

Yet as the half wore on, the pressure relieved, the Danes got tetchier, and Arnold’s men started to settle. Their only two genuine chances of the half both came through McGree, and neither truly tested Kasper Schmeichel, but getting to half-time with the scores level felt like a win in itself.

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That Ryan had completed more passes by the break than any of his teammates said it all. A classic game of two halves.

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