Wales coach Warren Gatland has identified Wallabies fly-half Bernard Foley as the danger man ahead of tomorrow morning's World Cup clash at Twickenham.
Foley, chosen ahead of Quade Cooper in the key games in the tournament, was outstanding in last week's 33-13 over England, scoring two tries in his 28-point haul.
"He's a real threat at the moment," Gatland said.
"He's a player we are conscious of and who can pose us problems."
The New Zealander also paid high praise to Australian coach Michael Cheika, saying his no-nonsense approach had worked wonders with the Wallabies.
"He's straight up and honest and the Australians respect and appreciate the way he approaches the job," Gatland said.
The sides are unbeaten and level at the top of Pool A with 13 points ahead of the match, and both will go through to the quarter-finals regardless of the outcome.
Wales has overcome a horror injury toll before and during its campaign, with Gatland making six changes to the side that beat Fiji 23-13 last weekend.
Cheika has been forced to make two changes to the line-up that beat England, losing outstanding flanker Michael Hooper to a one-game suspension and winger Rob Horne to a shoulder injury. Sean McMahon, man of the match in the game against Uruguay, will take over from Hooper, with veteran Drew Mitchell coming in for Horne.
Cheika has dropped lock Rob Simmons to the bench, his starting spot taken by Dean Mumm.
Wales captain Sam Warburton said he was disappointed Hooper would miss, saying it would have been an incredible challenge to go up against the vice-captain and fellow flanker David Pocock.
"I was looking forward to playing against both of them," Warburton said. "You don't get breakdown threats in the Northern Hemisphere as accomplished as they are."
Wales may have lost its last 10 games against Australia, but the skipper said the team preferred to focus on the fact it had won nine of its last 10 matches, the only loss coming against Ireland in a World Cup warm-up match in August.
"It would be an awesome achievement to finish top of the pool, and we are on a bit of a winning streak," he said.
WALLABIES: Scott Sio, Stephen Moore (c), Sekope Kepu, Kane Douglas, Dean Mumm, Scott Fardy, Sean McMahon, David Pocock (v-c), Will Genia, Bernard Foley, Drew Mitchell, Matt Giteau, Tevita Kuridrani, Adam Ashley-Cooper (v-c), Israel Folau. Reserves: Tatafu Polota-Nau, James Slipper, Greg Holmes, Rob Simmons, Ben McCalman, Nick Phipps, Matt Toomua, Kurtley Beale.