Will Genia is pushing hard to reclaim the Wallabies' starting half-back spot from Nick Phipps, with backs coach Stephen Larkham saying the former team captain is back to his dynamic best.

Genia has been fully fit only recemtly in recent seasons, with a spate of knee injuries curtailing his career, and another knee problem in a brave victory over the Springboks in July was yet another unwanted setback following an injury-plagued Super Rugby season. But Larkham said that Genia, still only 27, was ready to give the World Cup a serious shake.

"He's back," the typically measured Larkham said. "I think the games that he's played this year - he hasn't played many - but he's been much better than what we've seen. Earlier this year in Super Rugby he was somewhat hampered in the way he was playing but he's very motivated at the moment, particularly at this level. He's back to his full fitness.

"We don't want anyone to really overplay their hand in any position but he's got good balance with running, passing and kicking. And his defence is good as well."

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Genia played a key role off the bench in Australia's final warm-up thrashing of the United States Eagles, and, at his best, he is among the best half-backs in the world and a vital weapon at Michael Cheika's disposal.

Should his confidence dip, Larkham said "everything falls away".

"His running falls away, his confidence to kick falls away. But what we've seen this year is, he's back to where he needs to be."

Working in his favour is his strong combination with 2011 World Cup halves partner Quade Cooper.

Larkham said that final decisions had not been made about the final make-up of the team to face Fiji, noting that every possible pairing - including a Genia-Bernard Foley combination - had been given time together.

"Again, that combination's worked together; probably not as long as the other combination, but we've been chopping and changing every training run since we've been together this year," he said. "The nine is doing his job and making sure when he needs to take control of his team. Both of them are doing that well."