KINGSTON, Ont. -- It was an afternoon of rugby not for the faint of heart. One red card, three yellows and frequent visits by the medical staff.

Canada may wake up with bruises, but also a smile, after hanging on to defeat an undisciplined Tonga 36-27 in Pacific Nations Cup rugby play Saturday before a small but enthusiastic crowd on a grey, occasionally wet day at Richardson Stadium.

The Canadians wobbled at the beginning and end but put it together early in a second half that saw them score 27 points. Tonga rallied with 17 points through three consecutive late tries to cut the margin to 33-27 before James Pritchard booted his seventh kick of the day to ease Canadian concerns.

The win capped a remarkable week of rugby for Canada, which defeated Fiji 20-18 on Wednesday in Edmonton.

Canada is currently ranked 14th in the world by the International Rugby Board, behind No. 13 Fiji and No 11 Tonga. Coach Kieran Crowley's team has made a compelling case that the rankings should be revisited.

Perhaps more importantly, Canada defeated Tonga after having made 10 changes to the lineup that beat Fiji. Crowley, who raised his record at the Canadian helm to 19-13-1, has worked diligently to enlarge the Canadian talent pool and back-to-back wins over two Pacific Island nations make for gratifying payback.

The Pacific Nations Cup was expanded this year to incorporate Canada and the 16th-ranked United States as a way of boosting competition for the so-called Tier 2 rugby nations. Defending champion Samoa, currently ranked seventh in the world, bowed out to take part in a competition this month in South Africa in June against the Springboks, Scotland and Italy.

At 3-0-0, Canada leads the tournament standings. There have been mistakes along the way, but the Canadians have shown signs that their sevens flair is leaking into the 15-man game. And Crowley faces some interesting selection decisions despite missing key players like DTH van der Merwe, Jamie Cudmore and Phil Mackenzie.

Against Tonga, Canada also showed character and discipline. While the red mist descended on the Pacific Islanders, the Canadians refused to budge while declining to sink to the Tongan level.

The Tongans had one man red-carded in the first half and two more sent to the sin-bin in the second half.

Tongan prop Eddie Aholelei was sent off in the 34th minute after a melee that saw Canadian flanker Jebb Sinclair decked with a punch. Canadian fly half Nathan Hirayama and Tongan winger Fetu'u Vainikolo were lucky to stay on the pitch after trading blows early on in the incident.

Tonga was reduced to 13 men in the 52nd minute when Sione Piukala was yellow-carded for a shoulder change on Pritchard. And Tevita Halaifonua was yellow-carded for a hit that resulted in Canadian winger Matt Evans being stretchered off and Tonga playing temporarily with 12 men.

Evans later returned to the bench and seemed OK. But replacement Liam Underwood was felled as the clock wound down.

Tonga coach Mana Otai said the ill discipline probably came from frustration. But he said a review of the incidents failed to convince him such the sanctions were merited and he pointed to Hirayama as starting the melee that led to the red card.

As for the shoulder charges, he said the Pacific island teams were being unfairly penalized.

Crowley declined to debate the merits of the Tongan play.

"It was a physical game," said the former All Black. "We've got a few boys walking around pretty wounded in there and we've got to keep an eye on a couple of them, I think. We'll take stock of things (Monday)."

Canada has little time to recover with Ireland up next Saturday at Toronto's BMO Field. The Irish are currently ranked ninth in the world, although many of its top players are currently touring Australia with the British and Irish Lions.

Four days after the Irish match, Canada closes out tournament play against No. 16 Japan in Nagoya.

Pritchard, returning from a broken arm, scored a try and added another 18 points with his boot.

Evans and Sean Duke also scored tries for Canada while Pritchard contributed a try, four penalties and three conversions. Ciaran Hearn added a penalty for Canada, which had Tyler Ardron sin-binned in the final minutes for a technical foul.

Tonga got tries from Lua Lokotui, Viliame Iongi, Will Helu and Vainikolo. Kurt Morath, pulling the Tongan strings from fly half until he was hurt, kicked a conversion and a penalty while Viliami Hakalo added a conversion.

The win improved Canada's tournament record to 3-0-0 following the win over Fiji and a 16-9 decision over the U.S. Tonga, which defeated Japan 27-17 in its only other game, fell to 1-1-0.

Tonga, which trailed 9-7 at the half, does earn a bonus point for scoring four tries. Otai said there was no immediate word on the severity of the Morath injury.

Pritchard, returning from an arm injury, was good on all seven of his kicks. He also contributed to the offence, taking some abuse from the hard-hitting Tongans in the process.

There was good and bad on display from Canada early on. They pushed the pace but made mistakes off kickoffs -- one of which led to an early scrum that set up the first Tonga try -- and were hurt by handling errors. Good field position was also nullified by penalties.

But flanker John Moonlight caused several turnovers, prop Jason Marshall had a rampaging run and the Canadian backs were fluid.

Canadians fielded a more experienced squad Saturday with their starting lineup totalling 293 caps, compared to 149 for Tonga. Fifty of those caps came from Canadian captain Aaron Carpenter, who joins 13 others in the Canadian half-century club.

The grey day was brightened up by a handful of cheerful, colourful Tongan fans. The Canadian team did its bit to brighten up the antiquated venue by plastering the Maple Leaf outside their dressing room. And in a show of solidarity, they walked off the field after the warmup in a phalanx with hands on each other's shoulder. The Tongans did the same.

Canada is aiming to peak in August in a World Cup qualifying home-and-away series with the U.S.