The Kangaroos were solid in defence and clinical in attack as they thrashed the defending champions 34-2 at Old Trafford.
"I just think Australia's performance was nothing short of outstanding. We just couldn't get ourselves into the contest," Kearney told reporters.
"I thought the pressure they mounted - we were hanging on, last-tackle finishes and they came up with good points. I thought their performance was pretty faultless. They gave us a real lesson.
"When Australia play the way they did, we had to bring our best game today. I know we didn't do that. Australia certainly didn't allow us to play like that. The way they played took a lot out of us and that is as good as I have seen them."