Michael Cheika has leapt to the defence of Michael Hooper's decision to go for goal, rather than push for a fourth try, in the Wallabies' Rugby World Cup win over Fiji t Millennium Stadium in Cardiff, labelling the vice-captains call "logical".

Hooper, taking over the decision-making onfield after the benching of hooker and captain Stephen Moore, opted to take a penalty shot at goal with the Wallabies on the attack, and holding a 12-point lead, with 10 minutes remaining.

David Pocock scores the opening try for Australia against Fiji© Michael Steele/Getty Images

Bernard Foley duly split the uprights and Australia maintained the 15-point advantage until full-time but failed to match the four-try bonus point that England had secured in their first-up victory over the Islanders.

Hooper has attracted criticism for his decision, reporters considering the calls of Moore and Japan's Michael Leitch to chase match-winning tries rather than game-tying penalties against South Africa, but the obsession with five-point victories has surprised Cheika, who insists the plan of picking up four pool victories will negate any fear of "skimming through" in the 'Pool of Death'.

Cheika backed the call to shoot for goal, saying he'd make it "all day".

"I thought the logical approach is get out beyond two scores and then you do what you can from there," Cheika said. "That's the way rugby has always been played at Test match level, and I certainly am not going to disrespect the opposition because anything can happen.

"You give away an intercept try, or something happens, and then all of a sudden you are in a game where the other team scores and the crowd were behind them obviously.

"Anything can happen. You have to make sure of the result, and that's what [Hooper] did."

Another issue of concern for the Wallabies was the breakdown of their lineout, with Fiji taking command and winning three wins from Australia's throw after the substitution of Rob Simmons.

Cheika said there was no singular problem for the lineout woes - one steal came from a low throw, the second was stolen out of the hands of Dean Mumm, and the third resulted from a miscommunication in the raucous atmosphere at Millennium Stadium - "but it is an area I want to get sharper as well".

"Set-pieces you can only continue to improve because as teams watch you in the tournament they start making plans for what you are doing. So you have to keep changing little bits and pieces to make sure you are always one step ahead.

"We are going to meet plenty of challenges, as we are going to challenge the opposition in that area."