Winger Phil MacKenzie scooted over in the 73rd minute as Canada opened its campaign with a seesawing 25-20 win over Tonga on Wednesday, extending its unbeaten run against the Pacific islanders at the Rugby World Cup in Whangarei, New Zealand.

Aided by a strong tailwind, Canada took a 10-0 lead after 26 minutes and seemed to have the measure of the bigger Tongan lineup, but conceded a try on the stroke of halftime to surrender the ascendancy.

Centre Siale Piutau crossed twice as Tonga scored 20 of the next 23 points before Canada responded again with two late tries, then defended its five-point lead for the last seven minutes to clinch the vital Pool A win.

Canada has beaten Tonga in all three World Cup head-to-heads, dating back to the inaugural tournament here in 1987.

"That was awesome," Canada captain Pat Riordan said. "I'm so proud of the boys, the way they played.

"Just awesome. It just shows what the Canadian boys can do."

It was a second loss in five days for Tonga after a 41-10 defeat to No. 1-ranked New Zealand in the tournament's opening match last Friday night.

"We didn't play the way we wanted to play," skipper Finau Maka said. "Credit to Canada, they came out and defended well … controlled the ball well.

"They deserved to win."

The Tongans paid the price for taking the tactical decision to rotate 11 new players into the starting lineup after an opening loss to New Zealand.

Bearded flanker Adam Keleenberger was voted man-of-the-match for his tireless work containing the big Tongans at the breakdown.

"They did put a lot of pressure on us at the end, but our defence held up," he said. "It was great having the Canada chants."

Local organizers ran a promotion to "Paint the Town Red," and the citizens and visiting fans obliged with Northland Events Centre packed with fans wearing the colours and flying the flags of both national teams.

The Tongans wore their red jerseys in what was virtually a home game for them, the Canadians having to play in black.

The Tongans went out with clear intent to run the ball with flyhalf Taniela Moa spreading the ball wide at every opportunity. But they were let down by basic handling errors and a high-risk approach in the gusty conditions that backfired when they knocked on out wide trying to run the ball from deep inside their own quarter.

The Canadians capitalized in the 13th minute when lock Jebb Sinclair crashed over in the right corner after centre DTH van der Merwe's bumping run to finish off a movement that started behind halfway.

Fullback James Pritchard landed the conversion from the sideline and added a penalty 12 minutes later to make it 10-0.

The Canadians met the bone-jarring Tongan defence with some heavy hitting of their own, keeping the Pacific islanders scoreless until seconds before the break.

The Tongans scored just before halftime after relentlessly grinding away through the forwards on the left side, flyhalf Taniela Moa threw a long, looping cutout pass out wide to the left and Piutau sliced through the defence from 10 metres out.

Kurt Morath, who missed his first two shots at goal into the headwind, landed a more difficult conversion to make it 10-7 at the break.

Piutua combined again with Moa in the 53rd, charging onto a neat inside hand-off on the quarterline to cross untouched for his second try.

That gave Tonga the lead for the first time and Morath extended the buffer to 20-13 with a conversion and penalty before the Canadian fightback.

No. 8 Aaron Carpenter carried four defenders over the line with him in the 67th after charging runs from Van der Merwe and substitute Conor Trainor following a Tongan turnover near halfway.

Pritchard missed the conversion attempt which would have leveled the scores, but Canada maintained the attack, converting pressure into points when flyhalf Ander Monro found space with a solo dart inside the attacking quarter and then MacKenzie crossed in the next phase.

Canada next plays France on Sunday, while Tonga has a week before it takes on Japan.

Rugby World Cup 2011