Rob Kearney rued Ireland's failure to learn from their mistakes after last night's 16-0 defeat to Argentina.
Following the first Test of the series, in Santa Fe last weekend, Irish coach Eddie O'Sullivan said a lack of discipline was the reason for their 22-20 reverse, as his men gave away a string of possession and penalties.
And Leinster winger Kearney believes Ireland failed to address that weak point the second time around.
"Last week Eddie told us lack of discipline cost us the defeat, and in this Test there was no doubt that our handling was poor," he said.
"There were a lot of knock-ons and passes not going to hand. That was the reason for the defeat again.
"It's frustrating because we work on handling every day of the week, and not being able to produce it in a Test series is not good enough."
"We have to take the blame for that ourselves."
The 21-year-old Dublin-born player said that one personal positive on his debut was his ability to deal with the pressure at Jose Amalfitani stadium.
"From an individual basis, I think I was not shocked, which is an important thing," he added.
"If you can show that everything is okay it's positive for all the team."
After winning his first cap, Kearney is hungry for more and is determined to force his way into Ireland's World Cup squad.
He said: "Making your debut is always an important moment in anyone's career.It's about moving on and keeping working and trying to get that second cap."
Hooker Frankie Sheahan agreed with Kearney's assessment of the Ireland performance.
"We have to look at ourselves," he said. "We made a lot of mistakes.
"We dropped a few balls and suffered from a couple of turnovers."
But the Munster man added: "Scrummaging is getting stronger, with some good props that are coming through.
"It's a good Ireland side. We generated some pressure at the scrum."
Two defeats in two games in Argentina will come as a massive blow to the squad with the World Cup looming large on the horizon.
But Sheahan believes that the tournament in France this autumn is when Ireland will show their true colours.
"The score is quite disappointing," he admitted.
"A 16-0 (scoreline) obliges you to reflect onÂ how the game went."