The Socceroos meet the U.S. in Seattle on Friday, with both sides pumped up by home media and football pundits after winning their Group D openers against Turkey and Paraguay respectively.
Several U.S. commentators have written off Australia as a problem for the co-hosts, including former centre back Alexi Lalas who judged them an "average team by any measure" in his pre-tournament rankings of the 48 participating nations.
Foxe said there was no need to shield Australia's players from the outside noise.
"We can't baby them. They're their own selves, we want them to be their own selves," the former Socceroos centre back told reporters on Monday.
"Social media's out there, they're aware of media and the comments and what's being said.
"But we're concentrated on us. They're old enough and mature enough to understand what gets said and what doesn't get said."
Australia, who have never got past the round of 16, enjoyed a dream start in upsetting Turkey 2-0 with classy goals by livewire attacker Nestory Irankunda and Connor Metcalfe.
Irankunda said Australia's players were fired up by Turkey captain Hakan Calhanoglu describing his team as more talented than the Socceroos.
"It did piss off a few boys, but at the end of the day, these guys can talk all the s**t ... we don’t really care,” he told reporters.
Metcalfe said Tony Popovic-coached Australia would go into the U.S. match "full of energy, full of confidence".
Foxe warned his players not to get too carried away, though, reminding how everyone got excited at Qatar 2022 when Saudi Arabia upset eventual champions Argentina only to crash out of the group.
"Fantastic win against Turkey. Memorable, great. Enjoy that moment," he said.
"Now that's gone. Now we move on to the U.S."