Tonga beat England 30-12 in Perth on Saturday, with Haumole Olakau'atu playing all 80 minutes and scoring twice.
The Manly forward was asked by co-captains Jason Taumalolo and Addin Fonua-Blake to lead Tonga's Sipi Tau.
Approached on camp's second day, he had never led the dance and practised its words to avoid forgetting them.
He was moved to tears singing Tonga's national anthem: "It's very emotional when you get to sing your national anthem ... playing for your family and country and faith," Olakau'atu said.
He thanked coach Kristian Woolf for trusting him in his preferred position, saying three NSW State of Origin appearances had helped him stay confident when Tonga were on the back foot.
"I'll go again in game two, and this time hopefully I'll do it with a bit more enthusiasm and a lot more emotion," he said of leading the Sipi Tau against Lebanon on Friday.