Australia head coach John Connolly says choosing his most potent backline is proving troublesome after naming another revamped team for Sunday's clash with Ireland.
Tour skipper Stirling Mortlock has been shifted to inside centre after taking the number 13 jersey on his comeback from knee surgery in last weekend's 25-18 victory over Italy.
Lote Tuqiri returns to outside centre, the position he filled for the 29-29 draw with Wales before being switched to the wing in Rome, with Stephen Larkham reverting to his preferred outhalf role.
Mark Gerrard fills the vacancy at wing while Mat Rogers drops to the substitutes bench as Australia continue to field a different three-quarter line for each match of their European tour.
It could be a risky move, especially as the untested partnership of Mortlock and Tuqiri will be facing in-form Ireland centres Brian O'Driscoll and Gordon D'Arcy - a fact acknowledged by Connolly.
"It will be a good challenge for our centres to face O'Driscoll and D'Arcy," he said.
"We've been looking for the right combinations and it has been difficult. But we're confident of Stirling's ability to adapt to inside centre. He can play the ball as well as attack it."
Larkham has acquitted himself well in the number 12 jersey but will be grateful for his restoration at outhalf at the expense of Rogers, who endured a poor afternoon in Rome.
But Wallabies attack coach Scott Johnson has warned Larkham he may soon be on the move once again.
"Larkham is an intelligent kid - he's been around the block - but this is not the end of the experiment at outhalf," said Johnson.
"We're still trying to find the answers. I think Larkham has progressed again, even though he thinks he has been played out of position for the last few games."
Matt Giteau's re-conversion to scrum-half continues with the Western Force 24-year-old raising an eyebrow at the identity of his opposite number on Sunday.
Ireland have given a full Test debut to New Zealand-born Isaac Boss and Giteau has questioned the decision to select the Ulster half-back over veteran Peter Stringer.
"I was very surprised by the decision to leave Stringer out. I don't know what's going on in the selection process," he said. "Stringer's combination with Ronan O'Gara is outstanding. It was a big call."
Australia emerged easy 37-15 winners from their last meeting with Ireland in June but Connolly is expecting Sunday's Lansdowne Road collision to be a far tighter affair.
"Ireland are in better shape than when we played them in Perth during the summer," said.
"They're at the top of their game. Over the past 15 years, depth has been a problem but now they have solved that.
"This as good an Irish team as I've seen. They are probably the most experienced Test side in rugby and they have world-class players all over the pitch."
The only change Connolly has made in the pack sees Phil Waugh return at openside flanker in place of George Smith, who drops to the bench. PA
