Trailing 20-13, having led 10-0 until almost halftime, the Canadians were looking at defeat with 15 minutes remaining.
In previous World Cups, coach Kieran Crowley concedes, there would have been no coming back. So the elation won't be ignored, at least for one night, after late tries to No. 8 Aaron Carpenter and winger Phil MacKenzie earned the Canadians a 25-20 win Wednesday in the most northern of the 2011 World Cup venues.
"It gives guys confidence and self belief they can get over the line in these close ones," Crowley said. "Two or three years ago, I think we would have lost that. The confidence that they can actually nail it ... I think that's a real confidence booster for the guys."
Problem is, in four days they face an even tougher challenge against two-time finalist France.
"We'll give these guys a few hours and then we need to get their heads around France. We only have a four-day turnaround," said Crowley, who was part of the All Blacks squad that won the inaugural World Cup in 1987, the last time it was staged in New Zealand. "It's going to be challenging for us, playing Sunday."
"It makes me laugh really," Crowley added, not quite as an afterthought. "When Tier 2 countries have four-day turnarounds and (some) Tier One countries have seven-day turnarounds.
"But it is what it is. We knew what it was when the draw came out in the first place."
Flanker Chancey O'Toole was a casualty of physically brutal battle with the Tongans, leaving the field with an injured ankle and more than likely sidelined for the match against France.
"Doesn't look good at the moment. Probably going for x-rays," said Crowley. But, "the others are all bouncing off the walls down there."
Some teams at the tournament have saved players in certain matches to keep them fresh or available for other games in the pool. Japan has basically conceded defeat to New Zealand by naming a second-string squad, and France is considering sitting out many of its frontline players against the All Blacks as well.
Tonga even rested players against Canada only five days after losing the tournament's opening match to New Zealand.
Crowley doesn't have the same mindset. His aim is to finish third or higher in the five-team group, to earn automatic qualification for the 2015 edition. Canada reached the quarterfinals in 1991, but hasn't been close to repeating that in the four editions since.
"This is a World Cup, you go out there to try to win each game," he said. So, barring injuries, he'll be putting his best team on the field against France.
And why not, the way they came back was impressive.
"It's a tribute to them," he said, later joking: "Makes me proud to be a Canadian."
Crowley was appointed coach in 2008 and has focused on conditioning and cohesion to make the squad more competitive. When he told them to be calm, stick to the game plan and just tackle until they dropped against the Tongans, they did.
"Very pleased with that side of things," he said. "If Canadians have got one thing, they've got heart -- and they take things literally. So, I was very pleased with the way they stuck at it.
"These guys are some of the best professionals I've ever worked with, they just don't get paid. They'll run through a brick wall for you. They were able to do that tonight."
It extended Canada's unbeaten run against Tonga at World Cups to three matches.
Flanker Adam Kleeberger was voted man-of-the-match for his workrate against the Tongan pack which most critics thought would dominate the smaller Canadians.
"We've had belief in the team that we can take on any side," said Kleeberger, won of three bushy bearded players in the starting XV. "When we came home at the end there, I think we proved that to ourselves.
"It's always good to start with a win. Still got a long road to go."