Keira Bevan landed a penalty in the 85th minute to seal a dramatic 18-15 win for Wales over Scotland at the women's Rugby World Cup, while Canada and Italy also tasted victory in Whangarei on Sunday.
The first full round of matches at the tournament finished on a climactic note, as Wales held possession through 25 phases and earned a penalty, which replacement halfback Bevan calmly slotted before being embraced by team-mates.
It was easily the closest match of the opening weekend, with Italy beating the United States 22-10 and Canada overwhelming Japan 41-5 earlier on Sunday.
It followed comfortable wins for tournament heavyweights England, France and New Zealand in Auckland on Saturday.
Wales nearly paid heavily for their indiscipline, playing most of the final quarter with 14 players after prop Cara Hope and winger Jasmine Joyce were shown yellow cards.
Scotland capitalised, recovering from their halftime deficit of 15-5 to come level at 15-15 through two late tries to winger Megan Gaffney.
Wales, who conceded 18 penalties to five in a niggly affair, found some discipline and cohesion to march up the field in a compelling final passage to set up the win.
Wales back Hannah Jones said relief washed over the players when Bevan slotted the winning goal.
"Brilliant kick from Keira there. I had pure confidence, I knew she was going to get it over," Jones said.
"We've got to be disciplined for the next game, but brilliant shift from the girls, I can't fault them."
Scotland will rue a poor goalkicking performance from five-eighth Helen Nelson, who missed all five shots at goal, including several from close range.
Earlier, The Canadians secured a bonus point in their seven-try display, as did pool B rivals Italy, who beat the United States 22-10 in the day's first game.
Unfancied Japan were eclipsed in the forward exchanges, struggling to contain Canada's powerful rolling maul.
Tuttosi was the beneficiary, scoring all of her tries from close range.
"I think we've had really good buy-in since we started trying to make it into a weapon," said captain Sophie de Goede (23) about her forwards' strength in the maul.
"Overall it was a good game for us. We started strong, got to work some kinks out. I still think we have a stronger performance in us."
De Goede continued a unique family tradition when she led the team out, with her father Hans and mother Stephanie having both previously captained Canada at Rugby World Cups.
She said it was "special" to have both watching from the grandstand.
"They've been my heroes forever so to be able to follow in their footsteps, there's no words."
It was a straightforward win for the tournament's third-ranked side, although they lacked the flair of leading contenders England, France and hosts New Zealand, who attacked with freedom to win their opening games handsomely in Auckland on Saturday.
Half-back Brianna Miller crossed twice to help put Canada 27-5 up at half-time while the other tries went to wing Paige Farries and prop Mikiela Nelson.
Canada have reached the World Cup semi-finals four times and the final once, in 2014 when they lost to England.
Italy have never advanced to the knockout stages but they gave themselves every chance against the USA with an impressive win based on the brilliance of their backline.
A clash between the teams ranked fifth and sixth in the world was always expected to be tight and it was the higher-ranked Europeans who secured victory by pulling clear in the second half.
Up 7-5 at the interval, Aura Muzzo scored twice before the try of the match to fellow-winger Maria Magatti, who burst onto fly-half Veronica Madia's inside pass and ran 40 metres on the angle to score.
"It's very, very important," Valeria Fedrighi said of Italy's first ever defeat of the US.
"We've worked so hard over the summer and we've started on the right foot, it's incredible.
"We knew they are a very physical team. We just tried to play our game and we have done it."
Wales play Scotland later on Sunday.