Wales wing George North will move to the centre to face Australia as Warren Gatland makes six changes to his side.
Gareth Anscombe will start at full-back with the returning Liam Williams on the wing, while Justin Tipuric starts in the back row alongside Sam Warburton.
In the front row, Paul James and Samson Lee start in place of Gethin Jenkins and Tomas Francis while Luke Charteris will start in the second row instead of Bradley Davies.
Team Announcement Six changes @Gareth_Anscombe @SanjayWills @Paul_James1 Lee, Charteris and Tipuric all start pic.twitter.com/GLLC7gQty7
— Welsh Rugby Union (@WelshRugbyUnion) October 8, 2015
Alongside Charteris will be Alun Wyn Jones who will be winning his 99th cap at Twickenham.
North was in the midfield the last time Wales played Australia, impressing in a defeat that was Wales’ tenth consecutive against the Wallabies.
Another defeat here would not be catastrophic as their progress to the quarter-finals is already secured, but it would dampen team spirits as well as hand them a tougher route to the final.
Victory against Australia on Saturday and they will face either Scotland or Japan in the quarter-final. A loss would mean South Africa would be their next opponents.
Gatland will be under no illusions of the importance of this match, even though both teams have already qualified.
“Saturday is another huge encounter and both sides will be coming in with momentum and looking to top Pool A,” said Gatland.
“We have been impressed with Australia so far in this competition and we know a step up is required at Twickenham this weekend.
“It is still all to play for in terms of the knock-out phases.
“We’ve trained well this week, had a full squad to pick from and it is great to welcome back players from injury.”
Backs: Gareth Anscombe (Cardiff Blues), Alex Cuthbert (Cardiff Blues), George North (Northampton Saints), Jamie Roberts (Harlequins), Liam Williams (Scarlets), Dan Biggar (Ospreys), Gareth Davies (Scarlets).
Forwards: Paul James (Ospreys), Scott Baldwin (Ospreys), Samson Lee (Scarlets), Luke Charteris (Racing 92), Alun Wyn Jones (Ospreys), Sam Warburton (Capt) (Cardiff Blues), Justin Tipuric (Ospreys), Taulupe Faletau (Newport Gwent Dragons).
Replacements: Ken Owens (Scarlets), Aaron Jarvis (Ospreys), Tomas Francis (Exeter Chiefs), Jake Ball (Scarlets), Ross Moriarty (Gloucester Rugby), Lloyd Williams (Cardiff Blues), Rhys Priestland (Bath Rugby), James Hook (Gloucester Rugby).
