Struggling Wallabies prop Guy Shepherdson's hopes of retaining his key World Cup starting role rest on two testing training sessions on Tuesday.

Australia's selectors have pencilled in their 22 for Saturday's tournament opener against Japan in Lyon and bracketed Shepherdson with Al Baxter at tight-head.

The rising 25-year-old has easily been the Wallabies first-choice No.3 this season but question marks remain about his effectiveness as scrum anchor due to two leg injuries.

The nasty cork of the lower left quad in a training collision on the weekend, combined with recent right knee surgery, has left Shepherdson looking ginger since.

In contrast, the Wallabies selectors have been pleased by the training form of 47-Test prop Baxter, who played just a mere half of Test football in total as a benchman during the six-week Tri-Nations.

Apart from the crucial scrummaging position, Australia are expected to announce a predictable starting XV on Wednesday.

"Shepherdson is the only minor injury worry we have but everyone is good for selection," said coach John Connolly.

"In our minds we've bracketed Baxter and Shepherdson and we'll probably make up our minds (Tuesday) night.

"We just want to be comfortable exactly where Guy Shepherson's fitness is and also Al Baxter has done very well on the training paddock."

Baxter's selection in the 30-man squad raised more than a few eyebrows as it cost 130kg Queenslander Rodney Blake a place at the World Cup.

Blake is a far more threatening attacking weapon but can't cover the loose-head side of the scrum as well as Baxter.

If the 30-year-old NSW architect earns an unexpected start it will highlight his admirable effort in bouncing back from the 2005 Twickenham disaster where he was sin-binned for repeated collapses.

Connolly cleared lock Dan Vickerman for action after he missed Sunday's training session in front of 9,000 local fans with a suspected virus.

While he indicated there would be no surprises in the backline, with Chris Latham to return at fullback, more thought was required over bench spots and possibly in the back-row where Hugh McMeniman looms as an option.

Australia's pivotal second pool B clash against Wales in Cardiff on September 15 is at the forefront of the minds of selectors Connolly, Scott Johnson and Michael O'Connor.

"There's a couple of areas in the forwards that are up in the air that we have to discuss further," he said.

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