Ryan Jones is out of Wales' final World Cup warm-up game on Saturday against Argentina.
The back-five forward had been set to equal Ieuan Evans' 28 games as Wales captain, but has fallen victim to a calf injury.
Andy Powell takes over at number eight with Jonathan Thomas coming on to the bench.
Veteran flanker Martyn Williams takes over as captain as he returns to win a 99th cap.
Adam Jones, Lee Byrne and Leigh Halfpenny return after respective toe, knee and ankle injuries.
Stephen Jones is on the bench after recovering from his calf problem and will win a record 101st Wales cap if he comes on.
Wales coach Warren Gatland says he does not want to put the Osprey Ryan Jones' fitness at risk for the World Cup that kicks off for his side against South Africa in Wellington on Sunday, 11 September.
"We have withdrawn him [Ryan Jones] as a precaution and told him we are happy with what he has done so far in terms of making a claim for RWC selection," said Gatland.
"The 30-man squad will be named at the Millennium Stadium on Monday and, without getting ahead of ourselves, we have told him how important he is to us."
Ryan Jones, who had been due to start at number eight, played at lock in the 23-19 defeat by England at Twickenham on 6 August.
The 30-year-old was absent when Wales gained revenge last weekend with a 19-9 win at the Millennium Stadium
Jones saw the captaincy go to hooker Matthew Rees last season, but the Scarlets hooker has been ruled out of the World Cup with a neck injury.
In Rees' absence Sam Warburton took the captain's armband for games against the Barbarians, but he has been left out of the clash with the Pumas.
Dan Lydiate keeps his place at blind-side, while Andy Powell and Justin Tipuric provide the back-row cover from the bench as Sam Warburton and Toby Faletau are rested.
With Rees facing surgery and ruled out of the World Cup, Richard Hibbard - himself having just overcome a shoulder problem - gets the opportunity to stake his claim at hooker.
James Hook finished the win over England at fly-half, having started the match at full-back, and continues there against the Pumas, with Tavis Knoyle his half-back partner.
Jonathan Davies is reunited with Jamie Roberts in the centre, replacing the injured Gavin Henson, while Bradley Davies returns at lock in place of Luke Charteris.
Fly-half Stephen Jones makes a timely recovery from his knock to take a place among the replacements, as Rhys Priestland is sidelined for the Pumas showdown.
British and Irish Lions loose-head prop Gethin Jenkins remains unavailable for selection due to his long-standing calf problem that is set to rule him out of Wales' opening pool game with South Africa on 11 September.
"Criteria for selection has been about putting together a side to win the game, but also about giving some players the opportunity to impress and, therefore, bid for selection for the World Cup," said Gatland.
"In some areas we are also looking at combinations with that opening game against South Africa on 11 September always kept in mind.
"Beating the Pumas on Saturday would also mean we retain that all-important winning momentum going into the World Cup.
"But there are still many places up for grabs on that plane to New Zealand and the players all know they need to perform against the Pumas in order to further their own as well as the national cause."
Gatland will name his 30-man squad for the World Cup on Monday, 22 August.
Meanwhile, Former Leinster fly-half Felipe Contepomi leads an Argentina side including seven members of the squad that finished third in the last World Cup.
He is joined by Leicester winger Horacio Agulla and five of the pack, including veteran former skipper Mario Ledesma at hooker and Juan Fernandez Lobbe at number eight.
This is the first time Argentina's professional players have been together since their European tour last November, when they lost to Ireland and France after beating Italy.
The Pumas have a second warm-up match against Worcester before taking on England and Scotland in their World Cup pool next month.
Wales: L Byrne (Clermont Auvergne); L Halfpenny (Cardiff Blues), J Davies (Scarlets), J Roberts (Cardiff Blues), G North (Scarlets); J Hook (Perpignan), T Knoyle (Scarlets); P James (Ospreys), R Hibbard (Ospreys), A Jones (Ospreys), B Davies (Cardiff Blues), A-W Jones (Ospreys), D Lydiate (Newport Gwent Dragons), M Williams (Cardiff Blues, capt), A Powell (Sale).
Replacements: H Bennett (Ospreys), R Bevington (Ospreys), J Thomas (Ospreys), J Tipuric (Ospreys), L Williams (Cardiff Blues), S Jones (Scarlets), A Brew (Newport Gwent Dragons).
Argentina: Martin Rodriguez; Horacio Agulla, Marcelo Bosch, Santiago Fernandez, Gonzalo Camacho; Felipe Contepomi (capt), Nicolas Vergallo; Rodrigo Roncero, Mario Ledesma, Juan Figallo, Manuel Carizza, Patricio Albacete, Julio Farias Cabello, Juan Manuel Leguizamon, Juan Fernandez Lobbe.
Replacements: Agustin Creevy, Martin Scelzo, Mariano Galarza, Alejandro Campos, Alfredo Lalanne, Nicolas Sanchez, Juan Imhoff.
Wales' preliminary World Cup squad
Forwards: Scott Andrews, Gethin Jenkins (Blues), Lloyd Burns (Dragons), Huw Bennett, Ryan Bevington, Richard Hibbard, Adam Jones, Paul James (Ospreys), Ken Owens, Craig Mitchell (Exeter), Bradley Davies, Sam Warburton, Martyn Williams (Blues), Luke Charteris, Danny Lydiate, Toby Faletau (Dragons), Ryan Jones, Alun Wyn Jones, Jonathan Thomas, Justin Tipuric (Ospreys), Josh Turnbull, (Scarlets), Gareth Delve (Melbourne Rebels), Andy Powell (Sale Sharks).
Backs: Michael Phillips (Bayonne), Lloyd Williams (Blues), Tavis Knoyle (Scarlets), Jamie Roberts (Blues), James Hook (Perpignan), Jonathan Davies, Stephen Jones, Rhys Priestland, Scott Williams (Scarlets), Leigh Halfpenny (Blues), Lee Byrne (Clermont Auvergne), Aled Brew (Dragons), Shane Williams (Ospreys), George North (Scarlets).