Wales have opted for Rhys Priestland at fly-half in Stephen Jones' injury-enforced absence for Sunday's World Cup opener with champions South Africa.
James Hook is preferred to Lee Byrne at full-back, while George North gets the nod on the right wing ahead of Leigh Halfpenny, who makes the bench.
Luke Charteris partners Alun Wyn Jones in the second row, with Bradley Davies among the replacements.
Dan Lydiate and Toby Faletau join captain Sam Warburton in the back row.
All three, who have played only three games together as a unit, will be making their World Cup debuts.
The side shows three changes to the starting XV that beat England 19-9 at Cardiff's Millennium Stadium in the second of three warm-up matches in August.
Jonathan Davies continues his centre partnership with Jamie Roberts, while prop Adam Jones and hooker Huw Bennett complete the front row alongside Paul James.
Fly-half Jones, who needs one more cap to be Wales' most-capped international, sat out all warm-up games with a calf injury.
And his continuing problems gives Scarlets youngster Priestland, whose half-back partner will be Mike Phillips, an opportunity to win only his fifth cap.
The 24-year-old made his first start for Wales in the first warm-up match with England after Jones was forced to withdraw after pulling up minutes before kick-off at Twickenham.
Ryan Jones is another still struggling with a calf injury, so Andy Powell provides the back-row cover on the bench.
"We are going into this game looking for a win," said Wales coach Warren Gatland.
"If you get the world champions in your pool you want to play them first up and throw everything you've got at them.
"We've got the toughest group in the competition, but we know if we can come through we will be in good shape.
"The players have done everything we have asked of them so far, they have worked incredibly hard."
Wales have beaten South Africa only once in 25 attempts since 1906, and will face further games against Samoa, Fiji and Namibia in Pool D, with the top two teams progressing to the quarter-finals.
Wales: James Hook; George North, Jon Davies, Jamie Roberts, Shane Williams; Rhys Priestland, Mike Phillips; Paul James, Huw Bennett, Adam Jones, Luke Charteris, Alun Wyn Jones, Dan Lydiate, Sam Warburton (capt), Toby Faletau.
Replacements: Ryan Bevington, Lloyd Burns, Bradley Davies, Andy Powell, Tavis Knoyle, Scott Williams, Leigh Halfpenny.
South Africa: Frans Steyn; JP Pietersen, Jaque Fourie, Jean de Villiers, Bryan Habana; Morne Steyn, Fourie du Preez; Tendai Mtawarira, John Smit (capt), Jannie du Plessis, Danie Rossouw, Victor Matfield, Heinrich Brussow, Schalk Burger, Pierre Spies.
Replacements: Bismarck du Plessis, Gurthro Steenkamp, CJ van der Linde, Johann Muller, Willem Alberts, Francois Hougaard, Butch James.