The decisive period came in the final quarter when Contepomi first produced a moment of magic to set up the try from Hernan Senillosa that he then converted to push the Pumas into a 19-17 lead.
Ireland responded by driving into the heart of Puma territory and Duffy held his nerve admirably to land the difficult kick from wide on the right. Three minutes later however, Contepomi displayed all the attributes of the master craftsman to nonchalantly stroke over the winning kick.
And while there will be disappontment in the Irish camp that this one got away, coach Eddie O'Sullivan can be more than happy with this performance. In that final quarter Jerry Flannery landed a couple of massive hits to halt Argentine forward momentum, Gavin Duffy was safe as houses under the high ball while Mick O'Driscoll who had arrived on as a 69th minute replacement for Trevor Hogan, spolied two and robbed three Argentine throws on the bounce. Paddy Wallace had a good outing before being forced off injured to be replaced by Murphy while Carney took his try superbly and Hogan, Malcolm O'Kelly and Jamie Heaslip worked themselves to a standstill.
Wallace had given his side the lead with a penalty after just five minutes and there was nothing fortuitous about Carney's try two minutes later, the Munster man brilliantly reading Contepomi's attempted long pass to race in under the posts from half-way.
Contepomi put his side on the scoreboard with a 15th minute penalty and he landed a second in the 38th minute after Bryan Young was penalised for dropping a knee into the belly of the prone Marcos Ayerza, the Irish prop lucky to have remained on the field for his needless action.
Penalties from Contepomi either side of half time cut the Ireland lead to a single point but when the Pumas were forced to illegally halt an Irish rolling maul, referee Lyndon Bray had, quite correctly, no hesiitation in awarding a peanlty try.
A 56th minute Contepomi penalty was followed by a Duffy miss and then Contepomi weaved his magic to break the Irish line, pass to wing De Vedia who found Senillosa with the scoring pass.
Ireland: G Duffy (G Murphy temp); B Carney, A Trimble, K Lewis (B Murphy 79 mins), T Bowe (T O'Leary 79 mins); P Wallace (G Murphy 62 mins), I Boss (T O'Leary 77 mins); B Young (T Buckley 65 mins), J Flannery (B Jackman 77 mins), S Best capt; T Hogan (M O'Driscoll temp, 69 mins), M O'Kelly; N Best, K Gleeson (S Ferris 71 mins), J Heaslip.
Argentina: B Stortoni (Bristol); T De Vedia (Saracens), M Avramovic (Worcester Warriors), H Senillosa (Hindu), F Leonelli (Glasgow Warriors); F Contepomi (Leinster) capt, N Vergallo (Jockey Club Rosario); M Ayerza (Leicester Tigers), A Vernet Basualdo (Alumni), S Gonzalez Bonorino (Capitolina); P Bouza (Leeds), E Lozada (CASI); M Durand (Montpellier), JM Fernandez Lobbe (Sale Sharks), JM Leguizamon (London Irish). Replacements: M Cortese (Northampton Saints), JC Fernandez Miranda, H Agulla (both Hindu), G Fessia (Cordoba Athletic), J Stuart (both CASI), L Lopez Fleming (Edinburgh Gunners), P Cardinali (CSBJ Rugby).