Thousands of Socceroos supporters have poured into official live sites to soak up the atmosphere among fellow diehards ahead of the national team's World Cup clash.
Federation Square in Melbourne was a lockout after 10am as a sea of green and gold grew rapidly before Australia's match against Paraguay due to start at noon.
The site wasn't set to open to fans until 10.30am on Friday, a time that was pushed forward by an hour due to demand.
What followed was barriers knocked over as thousands of fans, mostly young men, streamed inside the gates.
It is unclear whether planned intensive security checks were able to happen as the crowd streamed through the entrance.
At least one flare made it through security, with fans cheering as it was let off not long after 11am.
Just after 10am, fans were told to make their way to nearby AAMI Park as Federation Square had reached capacity.
Inside, soccer fans young and old, mostly teenagers who should be at school for the last day of term, gathered to experience the "atmosphere" of watching with a crowd.
The teens, wearing a mixture of green and gold, black tracksuits and some wearing the Australian flag as a cape, were relatively well behaved, cheering and chanting as others bounced beach balls around the crowd.
Year 10 students Adrian, Jaxon, Ben and Xavier said they skipped school so they could be a part of the day, something their parents weren't aware of.
Another group of teens Atticus, Milla and Jonah said they had come to Federation Square with their parents' blessing given it was the last day of school term, and said they couldn't wait to cheer the Aussies home.
There was a noticeable police presence, with many officers wearing protective sunglasses and black helmets, watching the crowd from a distance.
Elsewhere, Tumbalong Park in Sydney's Darling Harbour is the city's flagship live site while Brisbane-based Socceroos faithful gathered at South Bank and Northbridge Piazza.
With a win or draw at Levi's Stadium in Santa Clara, Australia will finish second in group D, and face the Group G runners-up - one of Belgium, Egypt, Iran or New Zealand - in Dallas.
Defeat would mean a nervous wait, but the side could progress as one of the eight best third-placed teams.
Australian Associated Press