Emulating his NFL wide receiver dad, Freeman was the first to the ball when Sergino Dest's effort looped into the air, heading past Australia's 'keeper for the second goal in a 2-0 win.
Victory sends the United States into the knockout rounds of the World Cup they are co-hosting.
Right-back Freeman has played a vital role defensively too across two matches so far.
He follows in the footsteps of father Antonio, who most famously caught a touchdown in the Green Bay Packers' Super Bowl XXXI win in 1997, but also grabbed two in a Packers win at Seattle the previous year.
"For me that is a full circle family moment. I think for me it just shows how great the family tree is," said Freeman, after Friday's win.
"I think that just shows how he can be great, but I can be great in my own way as well.
"And I think that just shows how amazing it is to have a dad who's successful and that could mentor me to be able to be ready for moments like this."
One of the youngest members of the US squad at 21, Alex Freeman only made his senior international debut last year, selected by coach Mauricio Pochettino based on his Major League Soccer performances for Orlando City.
Arguably one of the less starry members of the US starting XI, he has nonetheless made the right-back position his own, fending off Timothy Weah and pushing Sergino Dest further up the field.
He also earned a move this year to Spanish club Villarreal.
"It's hard for me to kind of take it all in, but I think it's good also to kind of go through these challenges at such a fast pace at a young age," said Freeman.
"I feel like for me it's just going to make me an even better player to be able to kind of adjust the different atmospheres and be able to kind of adjust the different circumstances."
The popular Freeman was mobbed by his teammates including most of the bench after the goal, initially ruled offside, was cleared by VAR.
"I was very anxious to see whether it was a goal or not. And then when it was a goal, I looked back and I saw my teammates running out there and thought 'Oh Lord'... it just made me very emotional."
FIFA World Cup 2026
The 2026 World Cup will be held from June 11th to July 19th in the United States, Canada and Mexico. The tournament will feature 48 national teams and will be played in 16 modern stadiums.
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