Ireland coach Joe Schmidt feels the penalty Devin Toner gave away for a high tackle on Argentina's Nicholas Sancez was "milked for everything it was worth".
The game was finely poised at 23-20 to Argentina at the time and Schmidt believes the resulting penalty halted Ireland's momentum and tilted the game back in favour of the Pumas.
Schmidt said: "I thought Dev was a bit unlucky, at 23-20 I felt Sanchez - who was imperious today with his kicking and so many elements of his game - but I do think he milked that for everything that it was worth.
"Once it got to 26-20 it just made it that little bit more difficult, but that's not taking anything away from his or the Argentine performance.
However, the Ireland coach did acknowledge that the Pumas played superbly today.
He said: "The way they physically muscle you when they don't have the ball and the way they slow your ball down so that they have got nice set targets to line up and knock over.
"I think it makes it very difficult to play against them."
"We were lacking a bit of experience and a few cool heads to manage certain areas of the field. We were possibly over-committed at times and got caught short when they came down the wide channels. They certainly have some players with great footwork and pace."