Cahill was the man who provided the moments of magic in the 2-0 win over China on Thursday, opening the scoring in the minute with a bicycle kick before making it two on 65 minutes with a pinpoint header
It's not the first time that the former Everton man has been the hero for Australia, and Postecoglou was quick to praise the forward and his team's work rate.
“No one’s going to lie down, it’s a quarter-final,” said Postecoglou.
“They were working their socks off, they were closing our spaces and making it really hard for us but while they were doing it they were using energy and I said to the boys at half-time, just keep the ball moving and eventually they’ll break down.
“It took a Timmy special to do it, but once we got it we never looked back.
“I still think in that penalty box he’s world class,” he added of Cahill.
“We’ve managed him really well and we get the best out of him and maybe people will see some wisdom in us leaving him out against Korea.
“We’ve got to make sure that players like him, we use to the maximum of their ability and understand that we can’t just flog him out there.”
Next on the agenda for Australia is a semi-final clash with either Japan or the United Arab Emirates.