Finishing top of Pool A and avoiding New Zealand in the semi-finals is Australia's main objective, insists Wallabies scrum-half Will Genia.

Top spot is up for grabs when the Wallabies and Wales conclude their Rugby World Cup pool stage campaign in London on Saturday, with quarter-final qualification already assured.

Australia and Wales are level on 13 points after three games, but the Wallabies sit top on points differential after eliminating host nation England last week.

Topping Pool A would not only set up a last-eight encounter against the runners up in Pool B - probably Scotland - but avoid a semi-final showdown with reigning champions the All Blacks.

With that in mind, Genia and Co. are determined to end the stage as pool winners.

"It is another huge test match," Genia told reporters. "It is really important for us topping the pool.

"We just want to be consistent in all the things we do. Rugby can change so quickly in seven days.

"Those two games against New Zealand [where Australia claimed the Rugby Championship in Sydney before losing the Bledisloe Cup across the Tasman in August] showed that. That is probably driving the guys to train really well."

Australia are on a 10-game winning streak against the Welsh heading into the clash at Twickenham.

Wales have not claimed a Test victory over Australia since 2008, when they triumphed 21-18.

Interestingly, the Wallabies saw off Wales en route to their two World Cup victories in 1991 (pool stage) and 1999 (quarter-finals).

Genia added: "Every game we have played against Wales in the last 10 outings has been very, very close. We know how hard the challenge is.

"They will do their best to slow any quick ball we can get. The breakdown is going to be a big area for the lads."

Michael Cheika's Australia have made three changes to the starting line-up that faced England with Sean McMahon, Drew Mitchell and Dean Mumm coming in for Michael Hooper, Rob Thorne and Rob Simmons.

As for Wales, coach Warren Gatland has made six changes.