They came into it with high hopes after winning the Six Nations title, courtesy of four wins out of five, but their only reward after two fiercely committed 80-minute performances is the losing bonus point they picked up against the French.
There have been some eye-catching individual displays by Clarke's charges, with Simon Zebo, Ben Marshall, John Cooney and Paddy Butler among those showing well. However, collectively, Ireland are yet to hit top form.
A victory on Sunday over bottom-of-the-table Argentina would be a welcome boost, and head coach Clarke wants to see better execution from his players..
"For the next game, we have got to try and erase the mistakes. We are a good rugby side, any who watches us knows that there is no lack of attitude," he said.
"Our preparation is good in attack and defence, it is about execution now under pressure."
The Irish youngsters have showed signs of their attacking class, most notably when Andrew Conway rounded off a slick move for a try on the stroke of half-time in the 36-21 defeat to England.
They also cut the French to shreds when Zebo touched down in the Pool B opener, and team captain Rhys Ruddock knows his side will have to have an improvement, across the board, if they want to see off Los Pumitas on Sunday (kick-off 4.10pm local time/8.10pm Irish time).
"We gave away too many penalties, similar to the French game, where if they did get through we always seemed to panic and give away penalties.
"Whereas in fairness to them (England), they scrambled quite well. We made a lot of busts, but we weren't as clinical in terms of getting points when we were down there."
A smarter and more clinical approach will be needed against an Argentinian side that is sure to be voraciously backed at Estadio El Coloso del Parque. They had 16,000 spectators at their first game against England.
Summing up Ireland's second outing, Clarke admitted: "England took their chances and we didn't. We had a number of busts at key times in the game.
"I felt we were on the wrong end of some critical decisions which swung the balance of the game at times. Having said that, we contributed to our own downfall with some of our errors."
Click here to view highlights of the dramatic final ten minutes in the Ireland Under-20s' 25-22 defeat to their French counterparts, while you can also watch a full replay of the Ireland v England clash from Rosario.
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