Socceroos legend Tim Cahill's second-half brace sent Australia past China 2-0 and into the AFC Asian Cup semi-finals on Thursday.

Cahill opened the scoring shortly after the break before doubling the lead midway through the second-half with arguably the goal of the tournament as Australia reached the last four for the second successive time.

Ange Postecoglou's side will face either holders Japan or the United Arab Emirates in Newcastle on Tuesday for a place in the January 31 final in Sydney.

Shortly after Korea Republic punched their semi-final ticket with a 2-0 extra-time win over Uzbekistan in Melbourne, China got off to the better start as Australia, looking slightly nervous, struggled to settle into the game between the Group B winners and the Group A runners-up at Brisbane Stadium.

The Chinese strike-force of Sun Ke, with three goals from three games in the group stage, and Wu Lei caused problems for the Australian defence, calling goalkeeper Mat Ryan into action several times with their pace and ferocity.

But the good times would not last for China, who could have put Australia under serious pressure had they scored within the first 30 minutes. Controlling more than 77 per cent of possession in the first half, Postecoglou's men eventually found their feet, going close a couple of times before the break that allowed them to regroup for the second half.

And in the 49th minute, Cahill did what he does best - score in time of need for the Socceroos.

China cleared a corner from the right but Mathew Leckie headed right back into the box to keep the attack going. Cahill took advantage of a moment of freedom and hit an acrobatic overhead kick past goalkeeper Wang Dalei, who never saw it coming, reacting too late to the spectacular effort that put the hosts into the driver's seat.

The deficit forced China to come out, giving Australia more space to work with, and it was Cahill again who capitalised five minutes past the hour, powerfully heading home a cross from left-back Jason Davidson to make it 2-0 and effectively put the game out of their opponents' reach.