The Young Matildas must win their next match against Japan to secure a place at the world championships, after going down to South Korea in the semifinal of the Asian Football Confederation championship.

The Australian under-19 team lost 4-2 in Kuala Lumpur, ending its bid to become the AFC champion at its first attempt.

But the loss must quickly be forgotten with the Australians having to focus on winning the playoff for third against Japan on Tuesday.

Only the top three teams represent Asia in Russia later this year for the under-20 world championship.

In torrential rain, the semifinal match started disastrously for the Australians with two goals by South Korea in the first 15 minutes.

Lifting its game, Australia dominated the remainder of the half with Sasha McDonnell finally striking in the 40th minute.

But the South Koreans replied with another two second half goals before Australian captain Sally Shipard registered a consolation goal with nine minutes to go.

A disappointed Australian coach Alistair Edwards lamented the poor start.

"Not taking anything away from Korea, they took their chances well, but we are all disappointed that we let this one slip," she said.

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