Veteran forward Cahill, level on 29 goals with Damian Mori going into the game, netted a brace to write a new entry in the record books as the Socceroos raced into a 3-0 first-half lead at The Den.
The South Americans hit back in devastating fashion after the break, capitalising on their man advantage following Mitch Langerak's sending off to pull level and then win the game in injury time.
Speaking to Fox Sports, Cahill, who was subbed off with Australia still leading 3-2, made no secret of his satisfaction at reaching a new individual milestone.
"I feel fantastic," he said.
"It's a great moment in my career. Something you strive for as a kid, to achieve great things like this."
The New York Red Bulls man defended his team-mates after their capitulation, and hailed the new regime in place under head coach Ange Postecoglou.
"Overall I'm really happy for the team," he said.
"There's nothing to be ashamed of tonight. We played some amazing football. A few decisions went against our way and it's unfortunate Langerak got sent off. I feel we weren't scared to play, we wanted to attack.
"It's nice to be part of a set-up that's fresh, the boss has got his way of thinking. It's a really exciting time for us, being Australian at the moment."
Despite all the positives, Cahill said the new-look team will be feeling the pain of failing to win a game they led so comfortably.
"It's always great to say you've broke the record," he said.
"But performances, a win tonight or even a draw would have been a massive result. We take it to heart. Because as a team we're trying to build something special leading into this World Cup. The way we played, the way the boss changed the team, we only had one training session.
"I'm really proud of the team, but what I'm mostly proud of is the way we applied ourselves and the intent of what we were going to do and how we were going to do it. We weren't going to change our game for anyone.
"I'm proud of my moment but I'm more proud of these youngsters and what they're achieving. It's good times for Australian football."
Postecoglou meanwhile claimed his team should have been awarded more than one penalty by referee Lee Probert, and described Cahill as a worthy successor to Mori.
"He was fantastic tonight, he did his job really well," the coach said of his reliable frontman.
"He was really disciplined in his role. We asked him to do certain things defensively. When we got it (the ball) to get in the box and (there was) some quality delivery in there, he probably could have had another one. I thought we were unlucky not to get another couple of penalties to be honest.
"Yeah, he was fantastic and there couldn't be a more worthy person of that record because he's been an outstanding contributor to the national team."
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