Cheika raised eyebrows by revealing there are a host of positions up for grabs in his team for next week's quarter-final, justifying his decision to keep rotating players for the final pool game against Georgia.

Matt To'omua is the surprise choice at five-eighth while some key players such as captain Michael Hooper are demoted from the starting team for Friday's match in Shizuoka.

Four years ago, Cheika stayed true to a core team who were virtually unchanged through six of their seven games, only rested en masse against minnows Uruguay.

That team marched unbeaten to the final against the champion All Blacks.

The methodology has been turned on its head in Japan, with Cheika instead wanting his players on edge throughout what has effectively been a four-week pool stage trial period.

Cheika made 12 starting changes for last week's clash with Uruguay and another 10 this week, including the promotion of David Pocock to the captaincy.

He said the rotation was more appropriate for his current squad as there was greater depth.

"I think we've got a lot of competition with players that are very even in many positions," he said.

"I know that different teams have different strategies in how they want to approach it. Some want to go with the same players all the time.

"We feel like keeping players competing for spots is working for us, I think we're playing some good footy."

Cheika's analysis is contestable, with the Wallabies having failed to unleash an emphatic 80-minute performance.

Playmakers Christian Lealiifano and Bernard Foley have struggled to make an impact, resulting in the versatile To'omua's promotion.

Cheika said five-eighth was far from the only position on trial.

He confirmed Hooper would definitely line up in the quarter-finals - for what is likely to be his 100th Test - but that the squad's other back rowers were effectively on trial for the two remaining positions.

Jordan Petaia switches from the left to the right wing for just his second Test appearance and another bright display could hand him starting status for the knockout phase.

The omission of NSW Waratahs veteran backs Adam Ashley-Cooper and Bernard Foley suggest their quarter-final hopes are slim, having started only one game each.

Cheika hinted Reece Hodge may also struggle to reclaim a spot when he returns from a three-game suspension.

"You can train all you like but this is what happens. You give the other guys a look-in and they get a chance to play," Cheika said.

"That competition is sparking players to want to do better when they get on there every time because they know their place can be earned.

"Once qualified (for the quarter-finals), we'll be able to pick from the competition we've seen from the first four games."

WALLABIES

Kurtley Beale, Jordan Petaia, James O'Connor, Samu Kerevi, Marika Koroibete, Matt To'omua, Nic White, Isi Naisarani, David Pocock (capt), Jack Dempsey, Rory Arnold, Izack Rodda, Sekope Kepu, Tolu Latu, Scott Sio. Res: Jordan Uelese, James Slipper, Taniela Tupou, Adam Coleman, Michael Hooper, Will Genia, Christian Lealiifano, Dane Haylett-Petty.

Australian Associated Press