Australia and Iran booked their fourth World Cup finals appearances with nervous 1-0 victories in a dramatic finale to Asian qualifying on Tuesday.

South Korea joined them and Japan in qualifying for the finals after sneaking through on goal difference and Uzbekistan and Jordan retained hope of making it five Asian sides in Brazil after taking the third spots in the groups to set up a playoff.

The teams will meet over two legs in September with the winners taking on the fifth-placed side in South America in a similar playoff in November for a place at the finals.

That route was something most Australian fans were facing as their match against Iraq remained goalless with only seven minutes remaining and leading goal threat Tim Cahill having been substituted.

His replacement, though, turned out to be the saviour as Josh Kennedy, representing his country for the first time in over a year, was left free to head home a cross from the right and hand the Socceroos the win that secured a third consecutive finals appearance.

"At times you reach a phase in a game where you have to make things happen and it was about the time," Australia coach Holger Osieck told reporters after booking second place behind Japan in Group B.

That time never came for South Korea but a ninth appearance will as they slipped through on goal difference despite a 1-0 home loss to Iran in Group A.

The build-up to the match had seen Korea coach Choi Kang-hee going on the offensive, stating his side would beat Iran after he claimed to have been "badly treated" in the reverse fixture in Tehran last year.

The Koreans only needed a draw to ensure another appearance at the finals but they pushed and pressed for the win with their abundance of attacking talent, only to come unstuck against an assured Iranian backline.