Socceroos slip to second spot
Lee Jung-hyub scored the decisive goal just after the half-hour mark at the Suncorp Stadium, meaning South Korea should now face a slightly easier path than Ange Postecoglou's side in the knockout stages.
Australia piled on the pressure after the break in a bid to find an equaliser, but were unable to find a way past Kim Jin-hyeon in the South Korea goal and will now likely have to beat tournament favourites Japan if they are to make it all the way to the Asian Cup final.
Questions may be asked of Postecoglou, who opted to rest first-choice attacking trio Tim Cahill, Robbie Kruse and Matthew Leckie with the hosts' place in the last eight already secure.
The Australia coach threw all three of those players on in the second half, but it was a case of too little, too late.
Postecoglou's opposite number Uli Stielike also made wholesale changes, leaving star midfielder Son Heung-min on the bench once more.
Some robust Australia challenges throughout the game from the earned the ire of Stielike, who was forced to withdraw Park Joo-ho in the first half and Koo Ja-cheol early in the second due to head knocks.
After a cagey opening quarter of an hour, South Korea had the first clear cut chance of the match, but Kwak Tae-hwi sent his shot wide of the target.
Australia hit back with two chances in quick succession, but neither Tomi Juric nor Nathan Burns could beat Kim Chang-soo after creating space for themselves.
And it was Lee who broke the deadlock soon after, when he angled Lee Keun-ho's cross past Mat Ryan after the forward had been released by a delightful pass from captain Ki Sung-yeung.
The feistiness of the encounter went up a notch after half-time, with tensions threatening to boil over on several occasions.
South Korea were happy to sit on their lead, inviting pressure from Australia.
Nathan Burns almost found a way through when he went on a winding run through the visitors' defence, only to be thwarted by an excellent Kim save.
Kim was in excellent form, and not even the introductions of Cahill, Kruse and Leckie could force an equaliser as South Korea sealed their third 1-0 win from three Group A games.