Ireland earned their first Test win in Argentina as they overcame an under-strength Pumas side in Resistencia.
Two Jonathan Sexton kicks put Ireland ahead but the Pumas fought back to lead 10-6 as Manuel Montero scored a superb try after a Nicolas Sanchez break.
But a Chris Henry try put Ireland ahead before half-time and Sexton notched another touchdown after the break.
Andrew Trimble's intercept try added to Ireland's lead before Tomas de la Vega's late try for the home side.
Ireland captain Paul O'Connell made his 100th Test appearance in Saturday's game while Robbie Diack earned his first cap for Joe Schmidt's side with Kieran Marmion and Rodney Ah You also introduced for their Irish debuts in the second half.
Argentina were minus the vast majority of their frontline European players as the side was based largely around the country's second-string Pampas side.
Diack was guilty of wasting a glorious try-scoring chance for the visitors as he went for glory himself when Simon Zebo and Felix Jones were better placed after a fine break by Darren Cave.
Sexton did kick Ireland into a 10th-minute lead but the visitors then had a lucky escape as a kick from centre Gabriel Ascarate bounced into the touch with the Irish defence nowhere following a tap-and-go out of his own defence from Pumas skipper Martin Landajo.
A further Sexton penalty extended Ireland's lead to 6-0 but the Pumas responded with 10 unanswered points including giant winger Montero's brilliant finish as he fended off the Irish fly-half after a Sanchez break had totally outfoxed Luke Marshall.
The 36th-minute try helped Argentina into a 10-6 lead before the enthusiastic home crowd in the first ever Test match played at the Resistencia venue.
However, with number eight Benjamin Macome in the sin-bin after taking out Trimble in the air, they couldn't maintain their lead to the advantage as Ireland flanker Henry rumbled his way over the line straight after the restart.
Just four minutes into the second period, Sexton was on hand to round off a slick midfield wrap-around exchange with Luke Marshall although the fly-half missed the conversion.
After withstanding 10 minutes of heavy Argentinian pressure, which included a try-saving tackle from recalled Simon Zebo, the Irish put the game to bed as Trimble latched on to a floated Sanchez pass to sprint away to scored under the posts.
Sexton's conversion was one of his final contributions as he limped off with an undisclosed injury but replacement Ian Madigan quickly slotted two penalties to extend Ireland's lead to 29-10.
That margin was somewhat flattering to the visitors and De La Vega crossed for a late try which was converted by Iglesias.
The sides meet again in the Second Test in Tucuman next Saturday.
Argentina: Joaquin Tuculet, Santiago Cordero, Jeronimo de la Fuente, Gabriel Ascarate, Manuel Montero, Nicolas Sanchez, Martin Landajo (cpt); Benjamin Macome, Tomas de la Vega, Rodrigo Baez, Tomas Lavanini, Manuel Carizza, Ramiro Herrera, Matias Cortese, Lucas Noguera Paz.
Replacements: Lucas Gonzalez Amorosino for Cordero 65, Santiago Iglesias Valdez for Sanchez 69, Tomas Cubelli for Landajo 64, Bruno Postiglioni for Noguera Paz 74, Julian Montoya for Cortese 59, Nahuel Tetaz Chaparro for Herrera 59, Matias Alemanno for Carizza 41, Javier Ortega Desio for De la Vega 61
Ireland: Felix Jones; Andrew Trimble, Darren Cave, Luke Marshall, Simon Zebo; Jonathan Sexton, Conor Murray; Jack McGrath, Rory Best, Mike Ross; Iain Henderson, Paul O'Connell (capt); Robbie Diack, Chris Henry, Jordi Murphy
Replacements: Damien Varley for Best 68, Dave Kilcoyne for McGrath 62, Rodney Ah You for Ross 68, Devin Toner for O'Connell 68, Jamie Heaslip for Murphy 60, Kieran Marmion for Murray 60, Ian Madigan Sexton 64, Fergus McFadden for Cave 59.