Australia 32 Italy 6:Australia made a stuttering start but hit their formidable stride with four second half tries to overcome Italy in their opening World Cup match at North Harbour Stadium.

The Tri-Nations champions were held at 6-6 after a dour first half but scores from Ben Alexander, Adam Ashley-Cooper, James O'Connor and Digby Ioane saw them secure a bonus-point win in Pool C.

Italy's huge pack had severely tested the Wallabies in wet conditions in the first half, when the only scores came from two penalties apiece for Australia's Quade Cooper and Italian Mirco Bergamasco, but a three-try blitz in 10 minutes soon after half-time ended any hopes of an upset.

"We were very pleased with the effort, we had to work very hard in the first half but we got the benefit of that in the second half," said Australia coach Robbie Deans. "We stuck a foot in the door and got through ... we got a result which is what we came here for."

Australia have a habit of following big wins with poor displays and no victories come bigger than beating the All Blacks as they did two weeks ago to win a first Tri-Nations title since 2001.

Any complacency should have disappeared in the opening 10 minutes when, under a shower of rain, Cooper had to race into his own dead ball area to prevent Andrea Massi grounding a Luciano Orquera kick.

Italy's hopes of an upset, and first win over Australia, rested on bullying the Wallabies forwards and depriving their sometimes brilliant backline of ball.

The experienced Italian pack, inspired by skipper Sergio Parisse and hulking prop Martin Castrogiovanni, did their part but the 1991 and 1999 world champions conspired in their own frustration with a string of poor decisions.

"We didn't help ourselves in the first half, we were a little bit impatient in wanting that to come, we tried to force it," Deans added. "We overplayed our hand in the way that we attacked, I think we got the balance of our attack right in the second half."

Cooper put Australia ahead with penalties in the 17th and 27th minutes but Bergamasco hit back with two for Italy just before halftime, the second awarded when the Australian outhalf opted to run the ball out his 22 and was left isolated.

The mercurial New Zealand-born standoff had waltzed out of defence in the 36th minute only for his brilliant run to come to nothing when centre Anthony Faingaa was penalised for crossing.

It was Faingaa who gave way when O'Connor came on seven minutes into the second half and within two minutes the winger had helped the Wallabies score their first try.

O'Connor, who lost his place in the side after sleeping through the World Cup squad announcement, made an athletic attempt to dive across the line after a sweeping move but was stopped short and it was left to prop Alexander to wrestle himself over seconds later to break the deadlock.

Six minutes later, Cooper's shimmy and delayed pass allowed centre Ashley-Cooper to charge through a huge gap in the Italian defence and double the try tally.

O'Connor added the third on 58 minutes, scything through the defence to score after Cooper spotted his late run on the inside and cleverly switched the ball to him.

The many Australians in the 25,000 crowd had to wait another nine minutes for the next try with winger Ioane taking the honours after coming off his wing to finish a clever set move off the back of an attacking scrum.

Italy continued to press for a try, with a Parisse charge and a pushover attempt from a scrum offering their best chances, but the Australians held firm in defence.