Led by Jason Taumalolo, Tevita Pangai Junior and Joe Ofahengaue, Tonga were meant to cruise to victory in their World Cup nines opener against the Kukis.

Instead, the rising international powerhouse were humbled by 19-year-old Kayal Iro, who scored two tries in their shock 30-7 rout of the invitational team.

Iro, the son of former New Zealand star Kevin, as well as the nephew of coach Tony, has been in the Warriors system since moving to Auckland in 2016.

But the unknown flyer looked at home at Bankwest Stadium, where he sparked the minnow nation to a shock win over their highly-rated counterparts.

"It was just luck, eh," Iro told AAP.

"I know, there were some big names in that Tongan team. But we just came out hard and we knew we had to hold the ball against them.

"We did that, and then we got lucky again on the edges."

Tony believes there was more an element of luck to his nephew's breakout game.

"He's out of good stock. The apple doesn't fall far from the tree," he quipped.

"I don't think he's as fast as his old man, but he's got the same strength. He knows the way to the tryline and he's got a big engine. He can work all day.

"He's had a good year with the Warriors -20s. He's got a bit of class about him."

The victory comes six months after the Kukis demolished South Africa 66-6 in a qualifying match for the 13-a-side World Cup.

Kayal was the fullback in that contest.

"He's gotta get a little bigger and smarter. But he handles himself well," Kevin said.

"He played fullback for us in our World Cup qualifier against South Africa at fullback even though he hadn't played there much, and did a good job."

The shock result now gives the No.28-ranked Test nation a genuine shot at advancing out of what has been dubbed the pool of death.

Only one of Tonga, Samoa, Fiji and the Cook Islands can move into the final four.

With Tonga suffering defeat, Samoa now firm as the favourites to advance after pummelling the Fiji Bati 32-17 in the other pool C fixture.

Australian Associated Press