England called left-arm spinner Monty Panesar and fast bowler Sajid Mahmood into their team to replace Ashley Giles and James Anderson.
Australia named Andrew Symonds to take the place of the recently retired Damien Martyn.
England are 2-0 down in the five-Test series and need to win or draw this match to have any chance of retaining the Ashes.
If Australia win, they will regain the Ashes they lost to England in 2005.
Australia have not lost to England at the WACA since the 1978-79 series and have won their last four encounters against England here.
Australia - Ricky Ponting (capt), Justin Langer, Matthew Hayden, Michael Hussey, Michael Clarke, Andrew Symonds, Adam Gilchrist (wk), Shane Warne, Brett Lee, Stuart Clark and Glenn McGrath. Mitchell Johnson (12th man).
England - Andrew Flintoff (capt), Andrew Strauss, Alastair Cook, Ian Bell, Paul Collingwood, Kevin Pietersen, Geraint Jones (wk), Matthew Hoggard, Sajid Mahmood, Steve Harmison and Monty Panesar
Umpires: Aleem Dar (Pak), RE Koertzen (RSA)
Match Referee: Jeff Crowe (NZ)