A draw would have been enough for Australia to progress as Group A winners to face the second-placed team from Group B, but instead will face that group's winner which is likely to be tournament upstart China.
Cahill says the Socceroos must now concentrate entirely on the upcoming quarter-final so as to come out "all guns blazing" in the knockout match.
I'm going to focus on China. I know a lot about Chinese football and the league. These guys are very good. Technical, strong, they didn't get to the quarter-finals by luck. They're there because they deserve it.
"We need to get up and go again. We've got China in four days," Cahill said.
"Every game, you guys [the media] have said it's going to be a big test. Unfortunately tonight, you're going to focus on the 1-0 tonight, but I'm going to focus on China.
"I know a lot about Chinese football and the league. These guys are very good. Technical, strong, they didn't get to the quarter-finals by luck.
"They're there because they deserve it. I'm excited because there's a massive Chinese community in Australia, I'm a big fan of Chinese football and we've got to concentrate on ourselves.
"I'm not going ot be sidetracked by tonight's result because I know what we're going to do when we play China, and we're going to come out all guns blazing."