Australia will start the match as hot favourites after remaining unbeaten throughout the tournament while Pakistan, with one win so far, are vying with the West Indies for the right to meet them in the best-of-three finals.
The home side named allrounder Shane Watson 12th man and omitted pace bowler Michael Kasprowicz and batsman Darren Lehmann.
Kasprowicz was replaced by speedster Brett Lee on the bouncy WACA wicket.
The out-of-form Matthew Hayden and Adam Gilchrist will open the batting for Australia with Michael Clarke dropping down the order.
Conditions for the match were hot and the wicket was in perfect condition.
Australia: Ricky Ponting (capt), Adam Gilchrist, Matthew Hayden, Damien Martyn, Andrew Symonds, Michael Clarke, Simon Katich, Brad Hogg, Brett Lee, Jason Gillespie, Glenn McGrath, Shane Watson (12th man).
Pakistan: Inzamam-ul-Haq (capt), Shoaib Malik, Yousuf Youhana, Salman Butt, Abdul Razzaq, Shahid Afridi, Rana Naved-ul-Hasan, Yasir Hameed, Iftikhar Anjum, Mohammad Khalil, Younis Khan, Taufeeq Umar (12th man).