Tate McDermott returns at scrumhalf after missing the Pool C loss to Fiji with concussion and will link up with Ben Donaldson, who moves forward from fullback, in a new halves combination at OL Stadium.
Andrew Kellaway, one of the more experienced backs in a young squad, will make his World Cup debut at fullback, offering a more potent attacking weapon than Donaldson.
Jones has reacted to Australia losing the battle of the breakdown against Fiji by re-jigging his back row, moving Tom Hooper from blindside to openside and handing Rob Leota the number six shirt for his first start of the year.
Veteran flyhalf Quade Cooper and 125-cap openside Michael Hooper were two of the most surprising omissions from Jones's World Cup squad.
Porecki lines up in an unchanged front five and again replaces the injured Will Skelton as skipper with Jones ignoring the captaincy credentials of James Slipper, who starts at tighthead prop to win his 133rd cap, and vice-captain McDermott.
Pone Fa'amausili returns from injury to back up Slipper from the bench in the continued absence of the injured Taniela Tupou, while Matt Faessler is the replacement hooker in place of Jordan Uelese, who suffered an injury against Fiji.
The loss to Fiji leaves Australia needing to beat Wales on Sunday to guarantee they do not exit a World Cup in the pool stage for the first time.
"Every team has matches like this during a Rugby World Cup and for this young team it is this week," Jones said in a statement.
"We've prepared well, are focused on what we need to do, and we'll be ready to fight on Sunday night."
Team: 15-Andrew Kellaway, 14-Mark Nawaqanitawase, 13-Jordan Petaia, 12-Samu Kerevi, 11-Marika Koroibete, 10-Ben Donaldson, 9-Tate McDermott, 8-Rob Valetini, 7-Tom Hooper, 6-Rob Leota, 5-Richie Arnold, 4-Nick Frost, 3-James Slipper, 2-David Porecki (captain), 1-Angus Bell
Replacements: 16-Matt Faessler, 17-Blake Schoupp, 18-Pone Fa'amausili, 19-Matt Philip, 20-Fraser McReight, 21-Nic White, 22-Carter Gordon, 23-Suliasi Vunivalu.
