Canada finished the Sydney Sevens rugby tournament on a strong note Sunday, winning all three games on a day of controversy to win the consolation Bowl competition and finish ninth.

The Canadian men defeated Wales 32-21 and Scotland 35-12 before beating Samoa 17-12 on a pair of tries by Nathan Hirayama.

But the big story involved the two finalists.

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New Zealand beat Australia 27-24 in a thriller to win the inaugural Sydney event although it played the tournament's second day in the shadow of controversy lingering from the teams' first meeting.

Australia and New Zealand were drawn in the same group as Canada and, in the last pool match Saturday, New Zealand scored a stoppage-time try for a 17-17 draw with Australia that placed it atop Pool A. Television replays later showed New Zealand had eight players on the field at the start of the move that produced the decisive try.

World Rugby launched an investigation Sunday as New Zealand fought its way into the final and scored a try after full time for its second successive tournament victory.

Australia coach Andy Friend said it should act decisively to avoid a repeat of the bungle that could be especially embarrassing in an Olympic year.

"The question is how can that happen?" Friend said. "In an Olympic year, if that comes down to a gold medal game, well what's the point?

"Our boys, when they came off, they said they couldn't understand how they had the numbers out there. What we have to make sure is that those simple mistakes don't happen in a big tournament."

New Zealand also scored a try in stoppage time to beat South Africa in the final of last week's Wellington Sevens. Again, both of the finalists in Wellington emerged from the same pool and New Zealand's victory in the last pool match against South Africa was contentious; won with a try after the final siren.

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New Zealand, South Africa and Fiji are tied in first place in the Series standings after four of eight rounds. Canada remains 12th.

The circuit switches to North America next with stops in Las Vegas and Vancouver.

Canada lost to New Zealand, Australia and Portugal on Day 1 in Sydney.

But Liam Middleton's team bounced back against Wales on Sunday and led 22-7 at the half before the Welsh fought back to reduce the lead to 27-21. Sean White and Hirayama each scored two tries with singles from Adam Zaruba and Harry Jones.

Jones added three more tries against Scotland, with two from Hirayama.

Pat Kay also scored in the Bowl final against Samoa as Canada ran up an early lead of 17-0. Samoa is one of the teams Canada will be battling at the final Olympic qualifying tournament this summer.

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Sunday's final between Australia and New Zealand was one of the most thrilling in World Series history. Australia led through most of the match but New Zealand mounted a series of comebacks before finally snatching victory with a try to Reiko Ioane.

"We said it would take 20 minutes to win and we just kept on going and we got the victory in the end," New Zealand captain Tim Mikkelson said.

Australia scored first drew with a try by Henry Hutchinson who had come off the bench to score two second-half tries – including a sudden-death winner – in the quarter-final against England.

New Zealand levelled the scores with Reiko Ioane's first try which came from a powerful break down the left touchline by his brother Akira.

Hutchinson scored his second to give Australia a 12-7 lead but New Zealand immediately replied with a try to Kurt Baker. Next, Sam Myers put Australia ahead 17-12 and New Zealand again fought back with a try to Mikkelson to level the match at 17-17.

Australia seemed to have clinched victory when Greg Jeloudev scored less than two minutes from full time for a 24-17 lead. Ioane scored again but a missed conversion with 30 seconds remaining left the home side with a 24-22 lead.

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Then with the last play of the game Ioane achieved his hat trick and New Zeland sealed a 27-24 win. Australia was unable to join South Africa, who won in Cape Town, and New Zealand, who won in Wellington, in winning their home leg of the World Series.

World Rugby had the option after New Zealand's eight man error in pool play to award that match to Australia that would hand it first place in the pool. Australia preferred to stick with a draw that pitted it against England in the quarter-finals and avoided a rematch with New Zealand at the semi-final stage.

The decision paid dividends as Australia beat England 17-12 in an extra-time quarter-final, then upset pretournament favourite South Africa 12-7 to give itself the chance of its first World Series win in four years.

New Zealand beat the United States 24-7 in its quarter-final and World Series leader Fiji 14-12 in an ill-tempered semi-final.