Relieved Wallabies fullback Adam Ashley-Cooper has vowed to repay Robbie Deans' faith by finetuning his bombing radar for Saturday night's Tri-Nations decider.

Ashley-Cooper took Australia's record 53-8 loss to South Africa harder than most following a poor general-play kicking performance which left him and his chasers in "no-man's land".

Wallabies great and expert commentator Tim Horan was among many expecting the Brumbies utility to be dumped in favour of Drew Mitchell after his overcooked bombs simply handed possession back to the Springboks.

But Deans, who also watched Ashley-Cooper fail to execute the garryowen tactics in last month's 39-10 loss to New Zealand, has stuck by a nervous Ashley-Cooper who has gone back to school this week.

"I think everyone was pretty worried about that performance in South Africa, I certainly was," he said. "I took the loss pretty harsh, especially individually.

"I wasn't very happy with it, all my kick returns were off and I think that had an affect, an impact on the team's performance so hopefully we can rectify that this weekend.

"(Deans' selection) was a great boost and now I'm really really excited about it."

The up-and-under kick-return has become an almost universal tactic employed under the new experimental laws but Ashley-Cooper's efforts in Auckland and Johannesburg took the pressure off Australia's opponents as chasers had no chance to compete for the falling ball.

"Obviously the execution wasn't on, the kicks were too deep and I've been working pretty hard this week on those kick returns so hopefully this Saturday night I go out and return it and it pays good results for the team," he said.

"Putting it in the right spot and hopefully getting a good kick-chase and putting a lot of pressure back on their catch.

"It was a little bit of no-man's land, I suppose, it just came with the mis-communication of the back three. We were all off and that certainly reflected the performance."

A makeshift fullback following the season-ending injuries to Chris Latham, Julian Huxley and Cameron Shepherd, Ashley-Cooper has played his best Tests on the wing for the Wallabies and the New Zealanders are still pained by his tackle-shedding MCG try last year.

In his first Tri-Nations start, he burst past Richie McCaw, Rico Gear and Chris Jack to spark an Australian comeback which eventually saw them win 20-15.

Ashley-Cooper doesn't have to look too far to see what he must do right in hoisting garryowens, NZ playmaker Dan Carter continuously put them in the perfect areas at Eden Park, forcing numerous Wallabies turnovers.

The fullback knows he'll be targeted by Carter but says it's up to him to be one step ahead.

"It's basically knowing his left foot, knowing how he kicks and where he likes to put them," he said.

Carter didn't read anything into Australia's last-start eight-try capitulation and expected them to reproduce the form which scored the Wallabies a 34-19 upset of NZ in Sydney.

"We were in a similar position to where the Wallabies are at the start of the campaign with our backs to the wall and there's only one way to go ... so we see them as a real threat," he said.

Mystery still remains as to the identity of the Wallabies back-up playmaker with inside centre Berrick Barnes (shoulder) sidelined.

Deans won't reveal who would take Matt Giteau's place if he was struck down while assistant coach Jim Williams suggested skipper Stirling Mortlock may become the world's biggest five-eighth.

Reserve halfback Brett Sheehan played as a rugby league halfback for both South Sydney and Brisbane and looms as potential cover at No.10.

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