Substitute Josh Kennedy's goal seven minutes from time sent Australia into the World Cup finals for the fourth time on Tuesday, ending a nervous night for 80,523 rain-soaked fans packed into Sydney's Olympic Stadium.
Six minutes after coming on as a substitute for Tim Cahill, Kennedy rose alone in the centre of the penalty box to head Mark Bresciano's cross past the despairing dive of Iraq goalkeeper Noor Sabri and into the net.
The stadium erupted and Kennedy was mobbed by his team mates as they celebrated the goal that looked like it would secure the win they needed to seal second place in Asian qualifying Group B and the ticket to Brazil that went with it.
The Australians, frustrated for much of the evening by their own lack of penetration as much as the Iraqis, will now make their third successive trip to soccer's showpiece tournament and a fourth in total after 1974, 2006 and 2010.
"It's amazing for the country," delighted captain Lucas Neill said in pitchside interview.
"Three World Cups (in a row) now. I'm sorry guys, it wasn't pretty but we beat what was in front of us. Tonight let's look at the positives, Australia are going to Brazil!"
Iraq's hopes of qualifying were ended by last week's defeat at the hands of group winners Japan and Australia's victory also ended the slim hopes of Oman and Jordan, who meet later on Tuesday, of a direct passage to the World Cup.
Australia coach Holger Osieck had kept faith with the team who drew 1-1 in Japan and beat Jordan 4-0 in their last two matches to revive a lacklustre qualifying campaign.
Iraq, who lost stalwarts Younis Mahmoud and Nashat Akram to retirement after last week's defeat, fielded a young side with half an eye on the upcoming under-20 World Cup.
Goalkeeper Sabri, a survivor of the 2007 Asian Cup triumph, captained the side and it was he who turned Cahill's left-footed shot around the post after two minutes.
It proved to be a false dawn for the Australians, who, despite camping in the Iraq half, were unable to break down the visitors.
Defender Sasa Ognenovski headed the ball over the bar after 15 minutes and the next three chances fell to Cahill but he failed to hit the target with any of them.
The official team sheet indicated that Iraq had started with five forwards but their lack of adventure suggested otherwise and it was not until just before halftime that they got their first shot anywhere near the goal.
Saif Salman gave notice of a little more attacking endeavour from the Iraqis with a long range effort at the start of the second half which tested Mark Schwarzer in the home goal.
Australia continued to pour into the Iraqi half but the final ball was often poor and when the shots came they lacked the power to trouble Sabri.
Playmaker Tommy Rogic was introduced for Brett Holman in the 61st minute and immediately the tempo of the Australian attack went up.
Robbie Kruse found the net with a fierce shot four minutes later but the goal was disallowed for a Cahill push and the nervousness in the crowd, now soaked by incessant rain, went up another notch.
Cahill made his displeasure at being taken off after 77 minutes clear to Osieck but Kennedy, who last played for the Socceroos in late 2011, soon vindicated the decision.
Image: Joshua Kennedy celebrates after scoring the winning goal in the FIFA 2014 World Cup Asian Qualifier match against Iraq at ANZ stadium in Sydney, Australia.
Photograph: Cameron Spencer/Getty Images