'A little bit heartbreaking...'
A brace from Tim Cahill and one from the spot from new skipper Mile Jedinak gave the Australians an imposing 3-0 lead at the break, but Ecuador reshuffled their side in the second half and came out looking for goals.
After Ecuador scored soon after the restart, Australian substitute keeper Mitch Langerak was sent off for a rash challenge soon after coming on and the game turned completely.
Ecuador scored the resulting penalty and then clinched a late equaliser. As the game drew to a close, they finally found the winner to put Australia to the sword in the last minute.
Postecoglou had revamped his side for the game with a new backline and turned to his bench in the second half for an experimental line-up that looked good in attack but struggled in defence after going down to 10 men.
"Disappointed and a little heartbreaking for the lads that we couldn't hold out for at least a draw," said Postecoglou after the seven goal thriller.
"It was some useful lessons learned out of it and we exposed our young players to a whole new level of football in a pretty hostile environment. I think there were some massive positives for us.
"You prefer not to be in that situation and the game got a little bit out of control. They lifted their game and we just couldn't get hold of the ball unfortunately.
"It looked like we got a little bit tired and ran out of legs in certain areas. We made some mistakes.
"It's a good lesson in what you can and can't do."
Postecoglou took pride in the dominant first half display and had faith in his new look squad moving forward.
"I have absolute belief in what we can do and what our young players can do," he said. "The first half was very good.
"I think we caught them by surprise and they probably underestimated us a little. But ultimately it's about a 90 minute performance.
"But we exposed our players to a quality opponent in a pretty tough atmosphere and we learned our lessons and we paid a price.
"We can't let that happen again."