Irie swam a new record time of one minute 52.86 seconds to go under the old record of 1:53.94 set by American Lochte when he won the gold medal at last year´s Beijing Olympics.
Irie, 19, only three weeks ago missed the record by 8/100ths of a second in clocking 1:54.02 at the Japanese world championship trials, and continues his hot form.
The Osaka university student was also just 0.02 seconds outside American Aaron Peirsol´s 100m backstroke world record of 52.56secs here Saturday.
Irie said he was confident of breaking the world record again at July´s FINA World Championships in Rome.
"I am very happy to break the world record in Australia and I am going to break (the world record) again at the world championships," he said.
The Japanese sensation finished more than five seconds ahead of Australia´s Ashley Delaney and compatriot Takashi Nakano in third in the event.
"I couldn´t think I could go that fast," he said. "I can say only one phrase: unbelievable."
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