First five-eighth Maake Taulahi, one of a number of Rotorua players occupying a different position than listed in the programme, then decided it was time to take over.
The 19-year-old repeatedly chopped off his left foot inside his own territory before surging through and putting long-striding winger Latu Vaeno away to score.
Giant number eight Viliame Tosi - who is still eligible for under-16s despite the fact he might struggle to squeeze into an under-16 stone competition - then put his mark on the match.
Quick ball off the top of a five metre lineout found its way to the big youngster on the crash, and he found his way over the top of the defence to effectively decide the contest at 26-6.
Tauranga Boys' captain Connor Fifita got one back courtesy of a jinking run back against the grain, but that only provided slight respite.
The score was 40-13 within minutes - Vaeno galloped away to score his second following huge work from Tosi before Jone Lasaganibau scored another from inside the Rotorua half.
The hosts won the second half 21-7.
Rotorua Boys' went off the boil and were reduced to 13 players for a time, allowing Ben Webby, Harris Williams and Kemble Frost to add some respectability to a scoreline that had looked headed for anything but.
The result, and the manner in which it was reached, added another dimension to Central and Eastern Bay of Plenty clubs' threats of leaving the Baywide rugby competition next season.
Rotorua Boys' will play Wesley College next weekend for the right to play Hamilton Boys' High School for a place in the country's Top 4.
Rotorua Boys' captain Jessie Williams was thrilled he had not yet played his last game for the school.
"I was saying in the sheds before the game that it could have been my last game of the year - it's definitely motivation to keep it going," Williams said.
"It was awesome, the boys dug immensely deep in the first half. That was what we have been working on through the week. It's good to get a start like that and keep Tauranga on the back foot.
"You could see how dangerous they can be in the second half when they got a roll on and got their heads up a little bit."
He was relishing the prospect of a home match against Wesley. "We played Wesley at the start of the year and came off in a close game 17-15. It will be good to go back to back after a good season of rugby and play them with both teams at full strength."
Rotorua Boys' High School 47 (Latu Vaeno 2, Ngarohi McGarvey-Black, Maaki Taulahi, Jone Lasaganibau, Viliame Tosi tries; Corban Selwyn 6 cons) Tauranga Boys' College 34 (Connor Fifita, Ben Webby, Harris Williams, Kemble Frost tries; Sam Takai 4 cons, 2 pens)
