Ireland's men were edged out 4-3 by hosts Argentina in their Champions Challenge 1 opener on Saturday night.
The Irish looked in control after goals by John Jermyn, winning his 150th cap, and Timmy Cockram put them 2-0 ahead.
However, goals from Gonzalo Peillat and Lucas Vila levelled the contest before the interval.
Peillat and Vila hit further goals in the second half to put Argentina 4-2 up and while Michael Watt replied for the Irish, the hosts held on to win.
Coach Andrew Meredith, taking charge of the Irish for the first time, described the performance as "disappointing".
"There were some real positive phases where we looked good on the ball but there were far too many technical errors to really stamp our authority in any phase," said Meredith.
Ireland will have an immediate chance to improve on Saturday's performance when they face Japan on Sunday.
The Japanese played out a 4-4 draw with South Africa in their opener on Saturday.
The Irish team's participation in Argentina had been in major doubt until a late fundraising campaign.
Ireland starting XI: D Harte, C Harte, Gleghorne, Gormley, Jackson, Jermyn, Magee, McConnell, Caruth, Darling, Cockram