Lee Jeong-Hyeop's first half goal was enough to down Australia. PHOTO: AFP
Australia had been in form with two big wins so far, but Ange Postecoglou's rejigged side was dealt a setback after the Korean striker slid in to score on 32 minutes.
The Socceroos, who finish second in Group A, will now play China in the quarter-finals in hot and humid Brisbane and face a likely semi-final against holders Japan.
Australia threw everything at South Korea as they sought a vital equaliser, and Kim Jin-Hyeon saved brilliantly from Robbie Kruse when the substitute looked certain to score.
The game was not without controversy, with Park Joo-Ho and Koo Ja-Cheol both stretchered off and Matthew Spiranovic earning a caution that rules him out of their last-eight tie.
"I definitely feel that we could have got a draw out of the game," said talismanic forward Tim Cahill, who came on in the second half but was unable to rescue Australia. "Korea took their chance, full credit to them. But I definitely feel like we could have finished top of the group."
Oman salvage pride with Kuwait win
Abdul Al Maqbali struck with a second-half header as Oman beat Kuwait 1-0 in a dead rubber, both teams already having been eliminated.
A scrappy encounter between the Gulf rivals appeared to be meandering towards the tournament's first draw before Al Maqbali pounced with a superb header to break the stalemate in Group A game with only pride at stake.
It was Oman's first victory at the Asian Cup since 2004.
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