Wales scored two tries in the opening 10 minutes to give Jenkins something to smile about and were leading 12-7 before Thomas was first to go when he tried Irish referee Alain Roland's patience by holding onto the ball on the floor after conceding a penalty. Federico Tordeschini punished the Scarlets back row man even more with his first penalty and eight minutes later Wales were down to 13 men when Popham followed his clubmate to the sidelines for pulling down a driving maul.
This time the Pumas conjured up a try in the left corner for flying wing Jose Piossek as the eight man home pack shunted the six man Welsh scrum back towards their line. Tordeschini added the touchline conversion and then put his team eight points clear with a 45 metre penalty with the last kick of the half after Matthew Watkins had given away another silly penalty.
If the first-half ended poorly for the tourists, they couldn't have dreamed of a better start. Within two minutes they had sent Mark Jones diving in at the left corner for a try after Mike Phillips had taken a quick tap penalty in front of the home posts and then debutant lock Ian Evans galloped 60 metres to score a second try after 10 minutes having intercepted a rash pass by Augustin Pichot.
In between those two scores the Pumas grabbed a try back through flanker Juan Fernandez Lobbe after a Phillips clearance kick had been charged down. Even though the Welsh players thought the ball had gone out of play, Rolland was on hand to give the score.
While the Pumas were missing three players who were involved in the French Championship final, Jenkins travelled to Argentina without 21 leading players and was forced to give debuts to youngsters like Evans and his 20-year-old Ospreys colleague Alun Wyn Jones and he gave two more players their first games in the senior side in the second half when James Hook and Richard Hibbard came on.
Wales had to regroup in the second half and once they were back to 15 men they were able to secure enough possession to get the fleet footed Shane Williams into the game. The Opsreys wing made a number of telling breaks as the Welsh backs got going, although the only points came from the boot of Nick Robinson. Having missed from 45 metres either side of the interval, the Blues outside half hit the mark twice in the space of three minutes to bring Wales back to within two points with 20 minutes to play.
Now it was the Pumas' turn to panic and it was only their defiant defence, and the narrowness of the pitch, that saved them on a number of occasions. But as Wales tried to run from everywhere to breach the gap they conceded possession in their 22 and Franciso Leonelli grabbed a try which Tordeschini again converted.
That seemed to be the end for Wales but they never gave up and another debutant, replacement centre Hook, rounded off a magnificent break by Jamie Robinson to score a try at the posts in the third minute of injury time to help bring the tourists back to within two points.
Wales went for broke in the closing seconds, but couldn't break out of their 22 and conceded a penalty for holding onto the ball. The Pumas kicked the ball out of play and were delighted to notch their third victory over Wales and complete a whitewash of the northern hemisphere sides by their southern rivals.
Scorers: Argentina: Tries: J Fernandez Lobbe, J Piossek, F Leonelli; Cons: F Tordeschini 3; Pens: F Tordeschini 2
Wales: Tries: M Jones, I Evans, J Hook; Con: N Robinson 2; Pens: N Robinson 2.
Argentina: Juan Martin Hernandez (Stade Francais Paris); Jose Maria Nunez Piossek (Bayonne), Gonzalo Tiesi (London Irish), Rafael Carballo (Toulon), Lucas Borges (Stade Francais Paris); Federico Todeschini (Beziers), Agustin Pichot (Stade Francais Paris, capt); Rodrigo Roncero (Stade Francais Paris), Mario Ledesma (Clermont Auvergne), Martin Scelzo (Clermont Auvergne), Ignacio Fernandez Lobbe (Sale Sharks), Rimas Alvarez Kairelis (Perpignan), Juan Martin Fernandez Lobbe (Liceo Naval), Juan Manuel Leguizamon (London Irish), Gonzalo Longo (Clermont Auvergne)
Replacements: Marcos Ayerza (Newman) 68-72 for Leguizamon, Francisco Leonelli (Edinburgh Gunners) for Tiesi 67
Yellow Card: R Roncero 63
Wales: Lee Byrne (Ospreys); Mark Jones (Llanelli Scarlets), Jamie Robinson (Cardiff Blues), Matthew Watkins (Llanelli Scarlets), Shane Williams (Ospreys); Nicky Robinson (Cardiff Blues), Mike Phillips (Cardiff Blues); Duncan Jones (Ospreys, captain), Matthew Rees (Llanelli Scarlets), Adam Jones (Ospreys), Ian Gough (Newport Gwent Dragons), Ian Evans (Ospreys), Alun Wyn Jones (Ospreys), Gavin Thomas (Llanelli Scarlets), Alix Popham (Llanelli Scarlets)
Replacements: Richard Hibbard (Ospreys) for Rees 70, John Yapp (Cardiff Blues) for D Jones 79, Gareth Delve (Bath Rugby) for AW Jones 70, James Hook (Ospreys) for Watkins 52, Chris Czekaj (Cardiff Blues) for M Jones 75
Yellow Cards: G Thomas 30, A Popham 38
Referee: Alain Rolland (Ireland)