Wallabies coach John Connolly has revealed five-eighth sensation Berrick Barnes could shut out Stephen Larkham for a start in a World Cup semi-final, even if the veteran playmaker was declared fit.

Barnes, who cast aside a quad niggle at training on Wednesday, will start just his second Test at No.10 against Fiji in Montpellier on Sunday.

And it's a measure of his performance under pressure at Millennium Stadium that the 21-year-old has gone from the last man picked in Australia's squad to a player ready to edge out the indispensable Larkham.

Connolly said the three Test selectors would finely run the rule of Barnes's form in the final pool matches against Fiji and Canada before choosing their five-eighth to start the October 6 quarter-final.

"He's got to back up there's no doubt and I think mentally he's the type of young guy that can," Connolly said.

"I don't think he gets too carried away with his performance and he's trained well.

"He's got to play well this weekend and next weekend (against Canada) and it will make an interesting discussion."

Larkham knows he's no certainty to start in the quarters, probably against England, but wants a large amount of game time to be prepared for a semi-final rematch against New Zealand.

With Barnes possessing a stronger kicking game and boasting a fine ability to slot drop goals, Connolly wouldn't rule out starting the Queenslander against the All Blacks.

"It's possible, it's one match at a time but we were very impressed with his game last week," he said.

"It's a decision to be made in two weeks."

Both Barnes and powerful three-quarter Adam Ashley-Cooper proved their fitness for Sunday's clash by completing a lengthy team session.

"They're fine, Adam Ashley-Cooper was probably the most doubtful and his toe's come up well," Connolly said.

French journalists are starting to believe the Wallabies are serious contenders and have remarked how relaxed their players are.

It showed at a press conference when Ashley-Cooper and Drew Mitchell sat with the media questioning three of their fellow backs.

At one point Mitchell asked Barnes how he was after a late and high tackle by Welsh captain Gareth Thomas.

Barnes asked him who he was working for before replying.

Moments later Lote Tuqiri followed his response to a question from one reporter by asking 'What do you guys think?'.

Mitchell quickly piped up: "No Lote, we ask the questions here".

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