Wales are targetting victory over Argentina on Saturday as they look to build precious momentum going into the World Cup next month.
Warren Gatland's men kick-off their World Cup campaign against defending champions South Africa in three weeks' time and hope to arrive in New Zealand on a wave of confidence.
After turning the tide against England with a 19-9 win last weekend, the men in red are aiming to seal a second consecutive triumph in their final warm-up match at the Millennium Stadium.
But they will be without stand-in captain Ryan Jones, who is the latest to hand Gatland a World Cup scare.
The No.8 was set to equal Ieuan Evans' record of leading Wales in 28 Test matches but has been forced to withdraw after failing to recover from a calf injury despite taking part in cyrotherapy sessions.
Gatland could be forgiven for thinking Wales have been hit by a pre-World Cup injury curse.
They have already lost Morgan Stoddart, Gavin Henson and regular captain Matthew Rees, while Gethin Jenkins remains a major concern with a calf injury of his own.
Jones has missed previous World Cups through injury and Gatland is not willing to take any risks.
"Ryan's had a calf injury and we've spoken to him at length about the it and the risk of playing," said Gatland.
"We haven't named the final squad yet but he's very likely to be in it. There's no need to risk him and be in the position where we go to the World Cup without another experienced player."
Martyn Williams will captain the side in Jones' absence, as he wins his 99th cap, while Andy Powell slots in at No.8 and Jonathan Thomas moves up to the bench.
Elsewhere a trio of British Lions make their comeback from injuries.
Adam Jones replaces Craig Mitchell at tight-head prop, while Leigh Halfpenny and Lee Byrne join teen sensation George North in the backs.
Veteran fly-half Stephen Jones returns to the bench and will become Wales' all-time most capped player with 101 if called upon.
Gatland insists places are still up for grabs in the 30-man squad he names on August 22, and he has called on his charges to stake their claim by punishing the Pumas.
Gatland said: "Beating the Pumas on Saturday would mean we retain the all-important winning momentum going into the World Cup.
"We're fairly close to knowing the squad but there are a few places up for grabs. There could be a few bolters this weekend.
"A win would give us some great confidence but you can't underestimate Argentina. They have been together six or seven weeks, this is their one real warm-up game and they've picked a strong side. They have a big front five with a lot of players now plying their trade in Europe."
Felipe Contemponi captains an experienced side which also includes Rodrigo Roncero, Mario Ledesma and Juan Fernandez Lobbe.
Head coach Santiago Phelan said: "This is an important game as it's one of the few we have. Our main goal is to be in the best possible shape for England in our first World Cup match on September 10.
"Wales are at a good level and it will be very important for us to see where we are. But this is part of the preparation to get us in the best possible shape for the World Cup."
Players to watch:
For Wales: The old warhorse Martyn Williams will attempt to prove to coach Warren Gatland that he still has what it takes for one final hurrah at the world Cup with one of his typically energetic performances. Another player with a lot to prove is the controversial Andy Powell, who has often been seen to have more brawn than brains at times, although a tremendous asset when his head is screwed on right.
For Argentina: A number of the 'old guard' from the 2007 World Cup have hung on and need a strong showing to convince the coach they are able to keep up with the youngsters, as Juan Martin Fernandez Lobbe, Juan Manuel Leguizamon, Mario Ledesma and Rodrigo Roncero are all getting a little long in the tooth.
Head to head: The battle at flyhalf will be very interesting as James Hook is desperate to send a message to the selectors that it's his best position, having played at either fullback or centre in recent seasons with Stephen Jones and Dan Biggar preferred at No.10. Argentina have their own playmaker at pivot, as Felipe Contepomi can be a match-winner in any game.
2009: Wales won 33-16, Cardiff
2007: Wales won 27-20, Cardiff
2006: Argentina won 45-27, Buenos Aires
2006: Argentina won 27-25, Patagonia
2004: Wales won 35-20, Buenos Aires
2004: Argentina won 50-44, Tucuman
Prediction: Wales have looked good in their two previous warm-up games against England and will be determined to build on that. Argentina are a proud side who have consistently beaten top sides, especially in World Cup years, and will use their large pack to grind out control. The Welsh dragon is rising and will take another step on Saturday - Wales by 12.
Wales: 15 Lee Byrne, 14 Leigh Halfpenny, 13 Jonathan Davies, 12 Jamie Roberts, 11 George North, 10 James Hook, 9 Tavis Knoyle, 8 Andy Powell, 7 Martyn Williams (captain), 6 Dan Lydiate, 5 Alun Wyn Jones, 4 Bradley Davies, 3 Adam Jones, 2 Richard Hibbard, 1 Paul James.
Replacements: 16 Huw Bennett, 17 Ryan Bevington, 18 Jonathan Thomas, 19 Justin Tipuric, 20 Lloyd Williams, 21 Stephen Jones, 22 Aled Brew.
Argentina: 15 Martin Rodriguez, 14 Horacio Agulla, 13 Marcelo Bosch, 12 Santiago Fernandez, 11 Gonzalo Camacho, 10 Felipe Contepomi (captain), 9 Nicolas Vergallo, 8 Juan Manuel Leguizamon, 7 Juan Martin Fernandez Lobbe, 6 Julio Alfredo Farias Cabello, 5 Patricio Albacete, 4 Manuel Carizza, 3 Juan Figallo, 2 Mario Ledesma, 1 Rodrigo Roncero.
Replacements: 16 Agustin Creevy, 17 Martin Scelzo, 18 Mariano Galarza, 19 Alejandro Campos, 20 Alfredo Lalanne, 21 Federico Sanches, 22 Juan Jose Imhoff.
Date: Saturday, August 20
Venue: Millennium Stadium, Cardiff
Kick-off: 14.30 (13.30 GMT)
Referee: Romain Poite (France)
Assistant referees: Pascal Gauzere (France), Simon McDowell (Ireland)
TMO: Graham Warren (England)
AFP and rugby365.com
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