Tonga's 30-12 defeat of England at HBF Park in Perth has put the side in a strong position to reach the Rugby League World Cup semi-finals.
After withstanding England's early attack, Tonga led 10-0 at half-time. A Haumole Olakau'atu double and tries from Stefano Utoikamanu and Tolu Koula secured the win.
Jojo Fifita made his World Cup debut on the wing, running 157 metres from 14 carries, including 64 post-contact metres, with a line break and an offload.
Tonga and Dolphins coach Kristian Woolf praised the defence: "What I liked the most was the way we defended, we put ourselves under pressure a couple of times, but the defence was outstanding," he said.
Fifita, 23, had considered representing New Zealand and Australia before choosing Tonga after discussing his options with his partner and family.
His father represented Tonga at the Rugby Union World Cup. Fifita said, "Having the opportunity to run out for Tonga, I grew up watching Tonga."
Fifita said he had learned more about his heritage in the camp in less than a week than during the previous 23 years of his life.
He was in Tonga's squad for last year's Pacific Championships but missed the final selection. His family was proud he had been considered.
The debut capped a standout year for Fifita, who also made his State of Origin debut and scored twice for Queensland.
Tonga meet Lebanon at CommBank Stadium on Friday, then play Samoa on Sunday 1 November.