Ospreys prop Paul James comes into the front row in place of his regional colleague Adam Jones, who has a calf injury.
Cardiff Blues lock Bradley Davies starts in place of another Osprey, lock Alun Wyn Jones, with Jones moving to the bench.
Ryan Jones joins the back row in place of squad captain Sam Warburton, who is suspended, with Toby Faletau shifting from No8 to open-side flanker to accommodate the Ospreys flanker and fill the berth vacated by Warburton.
On the bench prop Ryan Bevington (Ospreys) provides front row cover in place of James and Sales Sharks back row Andy Powell is also added due to the promotion of Jones.
"We are sticking with the majority of the side which has put together a string of performances for us so far in this tournament, the one change which wasn't forced, in the second row, is based on the fact that Alun Wyn ran himself into the ground when we faced 14 men against France last week," said Wales head coach Warren Gatland.
"We face Australia back home at the Millennium Stadium in just over a month's time and we are single-minded in our assertion that we want that home-coming to be a celebration of us achieving the status of one of the top three teams in the world.
"We have come a long way and put together a string of performances that the nation can be proud of so far in New Zealand and we need to ensure that the history books reflect what we know we are capable of - and it is only by beating the Wallabies on Friday night that we feel this will be achieved."
WALES: Leigh Halfpenny; George North, Jonathan Davies, Jamie Roberts, Shane Williams, James Hook, Mike Phillips; Gethin Jenkins (c), Huw Bennett, Paul James, Bradley Davies, Luke Charteris, Dan Lydiate, Toby Faletau, Ryan Jones.
Replacements: Lloyd Burns, Ryan Bevington, Alun Wyn Jones, Andy Powell, Lloyd Williams, Stephen Jones, Scott Williams.