"I was doing the sprint; I came first, I think," McCarthy continued. "I didn't really know what to expect coming into it - you never really know.
"There were a couple of older guys, but I'm really happy with the day.
"I was with (Backler) on the swim and then got him through transition. I thought he was going to catch me on the bike but I managed to hold it and then kept it on the run.
"I felt really good in the swim, was feeling the legs a bit on the bike, but then got to the run and settled in."
The 16-year-old did not receive a medal, nor initially a pair of Jandals presented to the winners of the respective divisions.
Ironically, the humble youngster picked up the footwear as a spot prize, and took the confusion in his stride.
Next up are a couple of warm-up races before the secondary school nationals in Gisborne in late March, where he will compete in the under-19 category.
He may even come to appreciate his days of anonymity - if he continues with the form displayed over the Kaimais soon everyone in the multisport community will know his name.