Cahill was in everything from the outset and ensured the match would be over well before half time, banging in the opening goal in the ninth minute before earning a penalty seven minutes later that was calmly converted by Brett Emerton.

Qatar, who were already sitting back at the start of the match, were able to create a few opportunities in the first half but when Emerton grabbed his second with a sizzling strike in the 59th minute, any thoughts of the visitors snatching a draw were scuttled.

The Socceroos weren't done with and Josh Kennedy soon joined the party in the 76th minute to blow the score out to an embarrassing 4-0.

The win sees the Socceroos shoot clear to the top of their World Cup qualification group with two wins from two games and they will be looking to further enhance their chances of grabbing a top two finish and a finals berth in South Africa when they take on Bahrain away from home on November 19.

The start of the match was delayed by half an hour due to inclement weather, but the holdup failed to dampen the spirits of Cahill, who slammed home his 14th goal in 29 matches to further enhance his reputation as a game-breaker.

The Everton star, one of six changes to the starting line-up that defeated Uzbekistan 1-0 away last month, looked back to his best after his injury-enforced eight month absence from the Socceroos.

Some fine set-up work from Luke Wilshire and deft headers from David Carney and Kennedy saw Cahill find space at the back of the box and his finish was never in doubt.

After winning the penalty for the home side's second goal, the 28-year-old almost had another for himself when a defensive mix-up between Qatar keeper Abdulaziz Ali Abdulla and defender Ibrahim Majed almost resulted in Abdulla being caught off his line by a long shot from Cahill.

As Australia's control of possession and dominance of the game begin to loosen, Qatar looked to rebuild and Australian keeper Mark Schwarzer was first called into action at the 30th minute.

That shot was fired straight at Schwarzer, but forward Magid Mohamaed gave the veteran plenty more to think about 12 minutes later when he found space alone in the box, but Mohamaed wasn't able to work the angles.

Australia then started the second half briskly and it wasn't long before Emerton had his second.

Abdulla may have got a hand to his penalty strike in the first half, but the Qatar keeper could do little this time as he watched the ball scream past him after a good run from Emerton.

The match may have been well and truly dusted, but Australia continued to look dangerous and Kennedy was soon rewarded for a fine day at the office.

Star Qatari striker Sebastian Quintana, who was starved of service for most of the night, had a great chance in the 80th minute to make the score-line a little more reasonable for the visitors, but wasn't able to finish.

With Schwarzer beaten, there was only the recalled Craig Moore standing between Quintana and the goal, but he could only spray his shot over the crossbar.

The win continued Australia's recent dominance of Qatar, the Socceroos have now recorded 3-0, 3-1 and 4-0 victories over the Gulf state in their current World Cup campaign.

Australia 4 (Cahill 9, Emerton 16 (pen) & 59, Kennedy 76)
Qatar 0
34,320 at Suncorp Stadium