Sean O'Brien takes over from Warburton, Jamie Roberts replaces Brian O'Driscoll in the centre and scrum-half Mike Philips has recovered from a knee injury to start instead of Ben Youngs.
Alex Corbisiero returns from injury to replace Mako Vunipola, who moves to the bench, Richard Hibbard makes his first starting appearance at hooker, while Toby Faletau makes his Test debut at No.8.
Head Coach Warren Gatland said: "It all comes down to Saturday. Winner takes all. We know we can leave nothing in the tank and that only a complete performance will get us across the line. Picking this team was not easy and ultimately with several players available after recovering from injury the head overruled the heart in many selection decisions.
"It has been a challenging tour and we have had our fair share of injuries but we always knew that would be the case. Brian O'Driscoll is a great player and has had a wonderful career but for the final Test in Sydney we just felt Jamie Roberts' presence offered us something more.
"Mike Phillips and Alex Corbisiero were 1st Test selections and would probably have played in the 2nd Test if not for injury. Richard Hibbard, Toby Faletau and Sean O'Brien have also earned their starting places."
British & Irish Lions versus Qantas Wallabies, July 6, Sydney
15. Leigh Halfpenny (Cardiff Blues/Wales)
14. Tommy Bowe (Ulster/Ireland)
13. Jonathan Davies (Scarlets/Wales)
12. Jamie Roberts (Cardiff Blues/Wales)
11. George North (Scarlets/Wales)
10. Jonathan Sexton (Leinster/Ireland)
9. Mike Phillips (Bayonne/Wales)
1. Alex Corbisiero (London Irish/England)
2. Richard Hibbard (Ospreys/Wales)
3. Adam Jones (Ospreys/Wales)
4. Alun Wyn Jones (Ospreys/Wales, capt)
5. Geoff Parling (Leicester Tigers/England)
6. Dan Lydiate (Dragons/Wales)
7. Sean O'Brien (Leinster/Ireland)
8. Tangaki Taulupe Faletau (Dragons/Wales)
16. Tom Youngs (Leicester Tigers/England)
17. Makovina Vunipola (Saracens/England)
18. Dan Cole (Leicester Tigers/England)
19. Richie Gray (Scotland)
20. Justin Tipuric (Ospreys/Wales)
21. Conor Murray (Munster/Ireland)
22. Owen Farrell (Saracens/England
23. Manusamoa Tuilagi (Leicester Tigers/England)