As Felise Kaufusi likened the build-up to Tonga's Pacific Cup final campaign to an NRL grand final, Fonua-Blake said Kristian Woolf's side had to step things up against the Kangaroos.
Tonga qualified for Sunday's sold-out final at CommBank Stadium with a drama-filled 25-24 win over New Zealand.
Fonua-Blake was part of the only Tonga side that has defeated Australia in a Test in 2019 and said his teammates had to be wary of taking their foot off the gas if they wanted to clinch silverware .
"There's been a bit of chat during the week that we haven't won anything yet, this is the game that counts," Fonua-Blake said.
"We've been chipping each other and letting everyone know that this is the main game this weekend.
"The Aussies will be rested and they're going to come out firing.
"We have to try and replicate our start against the Kiwis and meet fire with fire."
Kaufusi, meanwhile, likened the fervour surrounding Tonga's charge to the Pacific Cup final to the buzz in the lead-up to an NRL grand final.
The 32-year-old, who played four Tests for Australia before switching his allegiance to Tonga in 2022, was a member of three grand final squads with the Melbourne Storm.
Tongan training sessions have been attended by thousands of fans in Sydney's west while the Kangaroos have been keeping a low profile with little fanfare in Wyong on the NSW Central Coast.
"This has a grand final week feel and I've been a part of finals campaigns and this is up there with that," Kaufusi said.
"The way our people have got around us and supported us we can definitely feel the love."
Tonga's players will be watched by members of the country's royal family.
This week they were given a reminder of how their rapid rise in international rugby league came to fruition when Andrew Fifita gave a speech in camp.
Along with Jason Taumalolo, Fifita was the trailblazer of the Tonga movement.
Andrew Fifita was initially derided when he swapped allegiances from Australia to Tonga. (Brendon Thorne/AAP PHOTOS)
Fifita was branded a "defector" when he declined a Kangaroos call-up to play for his father's homeland at the 2017 World Cup.
"The amount of crap he copped was pretty unfair," Kaufusi said.
"I didn't realise what Andrew went through just to represent his dad.
"We watched the video where he saw his grandparents in Tonga, they couldn't speak when he told them he was going to represent Tonga.
"He, Jason and Addin are part of our history for putting the red jersey first."
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