Toby Faletau moves to open-side flanker in place of Warburton with Ryan Jones filling the void at No.8 while prop Paul James gets the nod at prop following Adam Jones' calf injury against France.
In Gatland's only unforced change, lock Alun Wyn Jones is rested and replaced by Bradley Davies and the Kiwi coach has challenged his players to repeat the feat of 1987, when Wales also defeated Australia to finish third.
"We have come a long way and put together a string of performances that the nation can be proud of so far," said Gatland.
"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 that we feel this will be achieved.
"We are sticking with most of the side which has put together a string of displays.
"The one change which wasn't forced, in the second row, is based on the fact that Alun Wyn Jones ran himself into the ground when we had 14 men against France."
Wales team to face Australia:
15. Leigh Halfpenny - Cardiff Blues
14. George North - Scarlets
13. Jonathan Davies - Scarlets
12. Jamie Roberts - Cardiff Blues
11. Shane Williams - Ospreys
10. James Hook - Perpignan
9. Mike Phillips - Bayonne
1. Gethin Jenkins - Cardiff Blues
2. Huw Bennett - Ospreys
3. Paul James - Ospreys
4. Luke Charteris - Dragons
5. Bradley Davies - Cardiff Blues
6. Dan Lydiate - Dragons
7. Toby Faletau - Dragons
8. Ryan Jones - Ospreys
16. Lloyd Burns - Dragons
17. Ryan Bevington - Ospreys
18. Alun Wyn Jones - Ospreys
19. Andy Powell - Sale Sharks
20. Lloyd Williams - Cardiff Blues
21. Stephen Jones - Scarlets
22. Scott Williams - Scarlets