Sydney youngster Petratos squeezed in a shot from an acute angle on 23 minutes for the decisive goal in Ho Chi Minh City in Vietnam.

Earlier the Koreans had started the better with Australia goalkeeper Mark Birighitti forced into a good save from a free-kick after quarter of an hour.

Just over five minutes later Australia had their first genuine chance of the game through Mathew Leckie, before Petratos broke through a minute later with a shot which went in off the post.

South Korea's Lee Jong-Ho had a chance to equalise on the half hour mark but saw his effort in a one-on-one situation saved by Birighitti.

Australia took the foot off the pedal in the second-half and allowed Korea into the game, but they failed to capitalise.

Nevertheless, after the match Australia coach Jan Versleijen rued his side's inability to close out the contest.

"We had a good first-half where we scored the goal but I felt that we could have done better after the break to finish things off," he said.

Next up for the Australians is a date with reigning champions Thailand on Monday.