Genia, who has racked up 105 Tests for Australia, will end his international career at the tournament's completion, staying on to play with former Melbourne Rebels teammate Quade Cooper at Kintetsu in the Japanese Top Challenge League.

But first the 31 year-old wants to deliver in his last few games for the Wallabies - whether that be as at starting No.9 or from the bench.

The veteran of two World Cup campaigns in 2011 and 2015 said he would adapt to either scenario based on coach Michael Cheika's wishes.

"The main difference is when you start the game, you can sort of build into it. When you come off the bench you want to bring energy and an impact into the game but you don't want to try to do too much," said Genia, who was in the first XV in just one of this year's four Rugby Championship games but did start in the Wallabies' last Test against Samoa.

"Whatever role I am chosen to play in, whether it's from the start or at the back end of games, I am not particularly fussed. I'm happy to just contribute and do my best.

"I'm confident in my game and what I'll bring if given the opportunity."

Rather than seeing himself in competition with White - who is the only other halfback in the squad - Genia prefers to view what they can do as a pair.

"I enjoy the working relationship (with White) because we very much see the game in a similar way," he said from the Wallabies' base in Odawara, south of Tokyo.

"We have a similar sort of understanding as to how we want to play the game.

"Our styles really suit the type of rugby that we are playing at the Wallabies."

How to best utilise his No.9s isn't the only halves selection dilemma Cheika faces, with the coach also weighing up between Christian Lealiifano and Bernard Foley at five-eighth.

Foley has held down that role for much of the intervening years from the last World Cup, frequently with Genia, but Lealiifano and White were used as the starting halves for the two Bledisloe Cup matches in 2019.

Australian Associated Press