However, the handling errors from the Fiji loss came back to haunt the New Zealand team at the death of the game, as a wild pass being hacked ahead by Argentina saw them score in the corner with nine seconds left to win 19-12.
Koroi had left the field by then, having done his best and in fact exceeded expectations for the two days, while playing in front of his family who had made the journey to the capital to watch.
Sevens legend Tomasi Cama, who now co-coaches the team with Scott Waldrom in this new era, post Gordon Tietjens, felt they were justified to select the teenager just out of Feilding Ag High School school who did not play at the recent national tournament.
"He's probably better than me," Cama said.
"This is his first tournament and for a young fella he looks like he's been playing for a few years now.
"At this stage I don't have to do a lot [for him].
"He's got all the talent. If anything it's just the little things we can work on off the field to make sure that he gets out there and does what he does best."
Koroi impressed with his composure and speed off the mark.
The former Whanganui High School pupil admitted that despite appearances he had been very nervous in every game.
"Just like Junior [Cama] says, 'when you get out on the field, just play your game, stay calm under pressure because you're a playmaker, so just keep that in mind'."
Koroi, who got to start for the first time in his third match against the United States and then held that position on Sunday, had exceeded his own expectations.
"I was hoping to get a little bit of a run around on the field, but the opportunities I got, [you] just take them.
"Hopefully I work on them in every game I get and just keep working on it from then on."
