Australia stormed into the semi-finals of the Asian Cup after Harry Kewell's header deep into extra time sealed a 1-0 victory over Iraq.

Both sides wasted countless chances throughout a see-sawing encounter that seemed destined for penalties before Kewell's late intervention gave the Socceroos their first-ever semi-final berth at Asia's premier soccer tournament.

Kewell benefited from a sublime ball from the impressive Matt McKay and nodded home from inside the penalty area in the 118th minute to send the reigning champions out of the tournament.

Lucas Neill gave the Socceroos their real first sight at goal when he hooked a ball into the box that Brett Holman came close to prodding home had it not been for the intervention of Iraq goalkeeper Mohammed Gassid.

Brisbane Roar winger McKay was the next to go close when he pounced on Samal Saaed's poor clearance only to put his attempted chip over the bar.

Australia continued their early dominance as Sasa Ognenovski headed wide before McKay had another sight on goal but only managed to send his right-footed strike straight at Gassid.

Moments later, despite what looked to be a foul on Salam Shakir from Tim Cahill, Australia were through as Kewell's sharp turn left him one-on-one with Gassid, but the striker sent his lob over the bar when he should have scored.

Iraq should have had a goal of their own after the interval when Younis Mahmoud released Emad Mohammed whose subsequent shot trickled just wide of the left post.

Australia hit straight back as the impressive Brett Holman, along with Kewell and Mile Jedinak, all produced shots at goal before the hour mark.

The Socceroos had an ideal chance to take the lead after 65 minutes when McKay's corner was sent across goal by Neill, but Ognenovski could only direct his header from inside the six-yard box straight at Gassid.

Holman was full of attacking intent and twice tried his luck from distance with the second drawing an instinctive save from Gassid after a deflection.

Basem Abbas could count himself lucky not to be sent off for a terrible lunge on Kewell as Iraq threatened in the dying moments, with Mark Schwarzer's superb intervention denying Mustafa Kareem the winner.

Ognenovski had the best chance of the first period of extra time when his bicycle kick, destined for goal, was inadvertently headed over by Jedinak.

Neill was lucky not to give away a spot-kick for his last-ditch challenge on Alaa Abdul Zahra while substitute Scott McDonald failed to break his international scoring drought despite heading two attempts at the Iraq goal.

Iraq had chances of their own in the added period, the best coming when Mustafa Karim's cross was headed straight into the ground by Younis Mahmoud.

But just as a penalty shootout loomed, Kewell rose to meet McKay's precise delivery from the left to send Australia into the last four.