Young Dragons flier Will Harries partners Osprey Williams on the wing and fellow Osprey James Hook completes the back three by taking his place at full-back, while another Osprey Andrew Bishop partners Shanklin in the centre.
Up front the British and Irish Lions front row of Gethin Jenkins, Matthew Rees and Adam Jones is reunited with Scarlets captain Rees assuming the leadership duties of his national side for the first time.
The second row pairing of Alun Wyn Jones and Bradley Davies is retained from the All Blacks match and another young Dragon Dan Lydiate (23) joins the youngest player in the starting line-up, Blues flanker Sam Warburton, in the back row.
Osprey Jonathan Thomas is the last of just six players - alongside front rowers Jones and Rees, locks Davies and Jones and scrum half Phillips - to be retained from that final match of the summer tour, but he undergoes a positional switch to start at No 8.
From the bench veteran Martyn Williams could win his 100th international cap - including Lions Tests - and he is joined in backing up the forwards by Ospreys pair Huw Bennett (hooker) and Paul James (prop) and Blues colleague, second row, Deiniol Jones.
Blues pair Chris Czekaj (wing) and Richie Rees (scrum-half) are joined by Ospreys fly-half Dan Biggar to cover the backs.
"The front five virtually picks itself, when they're all fit and playing well," said Gatland. "There's two young boys in the second row there who have been going really well, Bradley in particular is in great shape and we will be looking to get the ball in his hands as much as possible, he is a real player for the future.
"There was debate in the back row and we decided we wanted to have another look at Sam who hasn't played for us since South Africa in the summer, when he did very well.
"We had options on the wing as well and we thought about Chris Czekaj at full back but in the end we've gone for experience there with James Hook and that then gives us a centre combination which retains experience too.
"At scrum-half Richie Rees has been putting pressure on Mike Phillips with some dynamic performances for the Blues so it's a big game for mike, we are looking for him to be physical and really lead the way.
"We are still hurting as a squad from the way the Wallabies beat us last year. They were impressive as a forward pack and they repeatedly won turnover ball which gave them the game.
"It's tough times out there for everyone at the moment and those fans who have put their hands in their pockets to support Wales today have made a real commitment to the cause already. We spoken about this week about the responsibility we have to those fans now to perform."
Wales: James Hook; Will Harries, Tom Shanklin, Andrew Bishop, Shane Williams, Stephen Jones, Mike Phillips; Gethin Jenkins, Matthew Rees (c), Adam Jones, Bradley Davies, Alun Wyn Jones, Dan Lydiate, Sam Warburton, Jonathan Thomas
Replacements. Huw Bennett, Paul James, Deiniol Jones, Martyn Williams, Richie Rees, Dan Biggar, Chris Czekaj