South Korea's Koo Jo Cheol, left, is congratulated by fellow team members after scoring a goal (Photo: AP)
The Socceroos will likely play reigning champions Iraq, also Saturday, for a place in the semi-finals in Doha. The current holders need just a point from their final group game against North Korea on Wednesday to make it through.
Australia, who were made to work hard for the victory, finish ahead of South Korea thanks to a slightly better goal difference, with Bahrain finishing third and whipping boys India last, without a point and having conceded 13 goals.
One of the pre-tournament favourites along with Australia, South Korea's victory against India was never in doubt -- the only question was how many times they would score and how soon.
Beneath pouring rain, the Koreans duly established a quick-fire 2-0 lead through Ji Dong-Won and Koo Ja-Cheol before striker Sunil Chhetri brought India back into the game from the penalty spot.
Ji swiftly restored the Taeguk Warriors' two-goal advantage but minnows India's stout defending meant the Koreans had to wait until the 81st minute for Son Heung-Min to net their fourth goal.
But the Australians did not have it nearly so easy against a Bahrain side who might consider themselves unlucky to have lost the match -- and be heading home prematurely.
Australia, who made the last eight at their maiden tournament four years ago but were knocked out by Japan on penalties, went into the match without the injured Luke Wilkshire, Jason Culina and David Carney.
Jade North, Carl Valeri and Matt McKay replaced them and as the game got underway in teeming rain Brett Emerton went close with a right-foot shot from the edge of the box that skidded just wide.
On a slippery pitch, Hamad Rakea also had an early sight of goal for Bahrain but sent his long-range drive sailing well over the bar.
With a small but vocal, drum-banging crowd cheering them on at Al-Sadd Stadium, Bahrain took charge as Australia struggled to assert any authority, using the flanks well and sending in some promising crosses.
Everton's Tim Cahill, up front with Harry Kewell once again, had Australia's best chance since the opening minutes when his powerful shot flew past the post on 17 minutes after Mile Jedinak won the ball.
The game started opening up and Bahrain had a great opportunity just past the half hour when their four-goal hero from their game against India, Ismaeel Abdulatif, hit the post from an acute angle on the right.
Seconds later and the ball was down the other end with Kewell, who had only the goalkeeper to beat, but took a touch too much and Mahmood Mansoor did well to block his shot.
A breakthrough looked inevitable and it came when Jedinak let rip from 30 yards, the ball bouncing once and past the flailing Mansoor.
Knowing they needed to win to stay alive, plucky Bahrain threw everything they had at Australia in the second period, but to no avail.