A goal from Mathew Leckie in the 60th minute led the Australians to a 1-0 win over Denmark in the early hours of Thursday AEDT, booking the Socceroos a spot in the knockout phase of the competition for the second time ever - the first since 2006.

A few hours later, Argentina put two goals past Poland to go from a first round loss to the top of Group C.

It means Australia, ranked 38th in the world, will face third ranked Argentina in an elimination match at 6am AEDT on Sunday.

Newcastle lord mayor Nuatali Nelmes said the match would be broadcast live on a big screen at Wheeler Place - the public space next to Civic Theatre.

"I encourage everyone to don their green and gold and get down to Wheeler Place to soak up the atmosphere and show their support for the Australian men's team," she said.

There were scenes of jubilation in venues across the Hunter from fans who not only braved the small hours but ventured out in green and gold to will the Socceroos to an unlikely win.

Mark Chegwidden, owner of the Crown and Anchor Hotel on Hunter Street, said his venue had a decent turn-out and "the vibe was great - especially when we got the win".

At the Cricketer's Arms in Cooks Hill, dozens were overcome with emotion both when Leckie beat Kasper Schmeichel to put the Socceroos in front and again when the full-time whistle sounded after six minutes of injury time.

Publican Amelia Hayes placed a $100 wager on an Australian victory - she used her winnings to shout the bar at the end of the match.

Many of the venues that opened for Thursday morning's fixture are looking to show the game on Sunday, while others are working through logistics.

The Socceroos' advancement into the round of 16 puts the current squad alongside the so-called golden generation, which included top flight European league players like Tim Cahill and Harry Kewell.

Clayton Zane, the former Newcastle Jets coach whose playing career included 14 appearances for his country from 2000 to 2001, told the Herald he thought Denmark looked "so sharp" early.

"The one thing [coach] Graham Arnold does is he galvanises the team and brings them together and he forms a really strong unit," Zane said.

"A lot of people are saying this is one of the not-so-strong national teams we've had in the last 20 years, but what he's done is created this real team ethic. The last two games, they've just been so resilient."

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