Minnows Japan face the tallest of World Cup orders against Australia on Saturday, but no more so than in the lineout where the Wallabies locks are in career-best form.

In an ominous warning to the small Cheery Blossoms pack, Wallabies skyscraper Dan Vickerman believes his second-row association with Nathan Sharpe has never been better.

Sharpe, who, at 200cm, is 4cm shorter than Vickerman, took out the 2007 John Eales Medal while his South African-born partner is back to his best after returning from shoulder surgery.

The seasoned pair have been Australia's top lock combination since the 2005 Tri-Nations and their form has seen former Test coach Eddie Jones rate them the key figures in Australia's developing forward pack.

"I really like playing with Sharpey," said Vickerman ahead of the pool B opener in Lyon.

"He's a fantastic player and I think the more you play with someone the more you get to know how they play and you complement one another's styles.

"I feel that over the last couple of years we're starting to get a bit of rhythm together so hopefully we can keep building on that and keep improving."

Vickerman justifiably rates Springbok pair Victor Matfield and Bakkies Botha the benchmark second-row pairing but indicated the gap was closing.

"They've been the form combination over the past few seasons and you measure yourself against the best and you always want to strive to get there," said the 28-year-old, who is poised to celebrate his 50th Test against Wales in 10 days.

"We obviously have our strengths and we look at their strengths and it's obviously them so we look forward to playing them."

Sharpe started in the 2003 World Cup final loss to England but Vickerman missed out after being dropped from the bench after Australia's quarter-final win over Scotland.

Fellow second-rower Mark Chisholm was rested from training on Tuesday in a sign he will not be in the 22 to play Japan when it is named on Wednesday.

Hugh McMeniman is expected to cover both lock and back-row positions.

Back-up halfback Sam Cordingley also sat out the session due to a groin twinge.

Meantime, Wallabies officials are set to test any player they suspect of drug use during the World Cup.

Coach John Connolly and manager Phil Thomson have told News Ltd random checks would be conducted in-house if a player showed signs of substance abuse.

Thomson confirmed that any positive test would be referred an ARU disciplinary committee.

Connolly said he had never seen evidence of drug-taking since starting his tenure last year.

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