Teenager Noah Lolesio was named man of the match in Tuggeranong's grand final win against Royals 29-17 after he stepped into the unfamiliar flyhalf role to fill the void left by injured captain Isaac Thompson.

The Vikings piled on the points in the first half, scoring four tries before the break and then hammering another nail into Royals' coffin with an 80-metre effort against the run of play after half-time.

The defending champions Royals did mount a late comeback, but fell short in their bid to win back to back titles for the first time in almost 30 years.

The win capped a whirlwind 12 months for Lolesio, who moved from the Gold Coast to Canberra two days after he finished school at the end of last year.

He is already in the ACT Brumbies' wider squad as a player of the future and showed poise well beyond his years to steer the Vikings around the field and eventually to another title for the Canberra rugby powerhouse.

"I can't describe the feeling. I moved down here two days after I finished high school at the end of last year, I did a pre-season with the Brumbies and here I am," Lolesio said.

"I've never played [flyhalf] in my whole life, this was the first year. [Coach Nick Scrivener] has put me everywhere, so it's an awesome feeling. I was ready to come to Canberra to play anywhere.

"I thought about staying at home but it was hard to refuse the offer in Canberra so to win one in my first season is an awesome feeling."

Royals almost got the perfect start to the game when Sam Carter charged down a clearing kick, but Ryan Lonergan won the race to the ball in the in goal.

From there the Vikings controlled the majority of the first half, scoring tries via Andrew Robinson, Henry, Gersekowski and Lonergan to skip to a lead.

The real knockout blow came when Robinson swooped on a loose ball and ran 70 metres for his second to open up a 29-3 lead.

Royals threatened to get back in the contest when Luke Kimber scored from close range and Lausii Taliauli finished a 100 metre attacking effort. In the end it wasn't enough.

Lolesio was the pick of the Vikings bunch, but the 12-point win was built on desperate defence by a group of players who refused to give an inch to Royals.

Hooker Michael Henry was tireless, Jordan Jackson-Hope added back-line spark, former Australian schoolboys captain Luke Gersekowski was a pest at the ruck and Ben Hyne was immense just a handful of games after making his comeback from a knee reconstruction.

The bad news for the rest of the competition is the Vikings are building a squad for long-term domination and boast some of the most exciting young players in Canberra.

Jackson-Hope is the oldest of the group at 22 years old, while Lolesio, Gersekowski, brothers Ryan and Lachlan Lonergan and Len Ikitau are only just starting their rugby journeys.

But the win was just as sweet for the older heads, including first-year coach Scrivener after he returned to the club this season.

Scrivener, a premiership-winning player for the Vikings, took control of the side when Tim Sampson moved to Perth and now has his first title as a John I Dent Cup coach.

"I was pretty jittery. The whole momentum of the game seemed to sway [in the second half] and everything was going their way," Scrivener said.

"We found a way to win and it was our defence right through the game. Our scramble defence showed how much these guys care for each other."

AT A GLANCE

John I Dent Cup: TUGGERANONG VIKINGS 29 (Andrew Robinson 2, Luke Gersekowski, Michael Henry, Ryan Lonergan tries; Ryan Lonergan 2 conversions) bt ROYALS 17 (Luke Kimber, Lausii Taliauli tries; Pedro Rolando 2 conversions, penalty) at Viking Park on Saturday.

OTHER GRADES

Women: TUGGERANONG VIQUEENS 32 (Tayla Stanford 2, Ema Masi, Regan Hart, Nora Lal tries; Emily Sogal 2 conversions, penalty) bt UNI-NORTHS OWLS 8 (Dana-Louise Deklin try; Bridgette Cunningham penalty).

Second grade: QUEANBEYAN WHITES 37 bt TUGGERANONG VIKINGS 8.

Colts: TUGGERANONG VIKINGS 29 bt QUEANBEYAN WHITES 12.

First division first grade: ADFA 19 bt TUGGERANONG VIKINGS 17

First division second grade: RMC 24 bt TUGGERANONG VIKINGS 17