The second day of the £250,000 tournament saw the first round conclude with eight Pairs games, with three seeded nations exiting in the opening three games on a night of shocks.
New Zealand's Rob Szabo and Warren Parry kicked off the drama by knocking out Canada's three-time World Champion John Part and Ken MacNeil with a narrow 5-4 game in a see-saw opener.
The Canadians hit back from a 2-1 deficit with an 80 finish from Part and a 120 checkout from MacNeil as they moved ahead, only for Szabo to move the Kiwis ahead by taking out 102.
Part forced a deciding leg, but Parry finished 92 to give New Zealand a 5-4 win for their first World Cup victory since the inaugural event in 2010.
"It was a great battle," said Szabo. "We'd been discussing what our game plan was going to be during the week and it worked in our favour and I'm grateful that we got the win.
"The feedback we've been getting over the last few days from home has been phenomenal and they were getting up early in the morning to watch this game, so to get the win is the icing on the cake.
"We look forward to the second round and we've got room to improve and we can do better, but we'll enjoy this moment and then see what happens tomorrow."
That success was followed by a superb display from Hungary as they knocked out Sweden 5-2 to claim their own maiden World Cup victory, as left-hander Nandor Bezzeg and debutant Gabor Takacs.
Sweden's Magnus Caris and Daniel Larsson had led 2-1 early on, but Bezzeg's 67 checkout levelled after two misses from their rivals, before Takacs landed the winning double in the next three legs to record a memorable win.
Hong Kong's Ting Chi Royden Lam and Scott MacKenzie then knocked out a third seeded nation of the evening as they overcame Welsh duo Mark Webster and Jamie Lewis 5-3.
Webster - part of the Welsh team which reached the 2010 final - took out 72 and 95 to help his nation into a 2-1 lead, only for Hong Kong to take the next three, including a 131 checkout from Lam, to move 4-2 up.
Tops from Webster saw Wales hit back, but Lam landed double ten in the next to seal Hong Kong's progression to the last 16.
"We're delighted to win this game," said Lam. "I was so nervous that my hand was shaking - but that shows what it means to us and also all our supporters who stayed up during the night in Hong Kong to watch us."
Holders Netherlands, meanwhile, booked their spot in the second round with a strong display as Michael van Gerwen and Raymond van Barneveld overcame American pairing Darin Young and Larry Butler 5-2.
Van Gerwen kicked off the game with a 150 finish before checkouts of 105 from Young and 100 from Butler saw the Americans pull back to 4-2, but van Barneveld applied the finishing touch with double 16.
"America was one of the toughest draws which we could have got so it's a good result for us," said van Barneveld, a two-time World Cup winner.
"It's totally different to any Singles competition but we know what we can do and we'll play well in the next round. We're used to playing Singles matches so that will suit us on Saturday but we play well as a team too."
The Dutch pair now take on South Africa in the second round, after Devon Petersen and Graham Filby prevailed 5-4 in a deciding leg against Finland.
The Finnish pair of Kim Viljanen and Marko Kantele led 2-0 and 3-2 - despite checkouts of 75 from Petersen and 93 from Filby, who also hit the winning double in back-to-back legs to move South Africa 4-3 up.
Viljanen levelled on double four, but Kantele missed one dart at tops for the match in the final leg - to complete a 120 finish - before Petersen stepped in to take out double ten for victory.
Number two seeds Scotland, represented by World Champion and Premier League winner Gary Anderson and world number five Peter Wright, overcame Singapore's Paul Lim and Harith Lim 5-1 to move through to face Hungary.
The game was unique for Wright hitting all five winning doubles for the Scots, who led 4-0 before experienced ace Paul Lim finished double top, and a second 180 of the game from Wright helped the Scots seal their last 16 spot.
Ireland's William O'Connor and Connie Finnan recorded the night's only whitewash as they knocked out Polish debutants Tytus Kanik and Mariusz Paul to set up a second round date with Hong Kong.
Last year's semi-finalists Northern Ireland, represented again by Brendan Dolan and Mickey Mansell, overcame a slow start against Thailand before recording a 5-2 triumph.
The Thai pairing of Attapol Eupakaree and Thanawat Gaweenuntawong shared winning doubles as they took a 2-1 advantage, but Dolan finished 58 and 61 to move Northern Ireland ahead before taking out 61 to claim a fourth successive leg as they set up a second round tie with New Zealand.
The second round sees the ties kick off with two Singles games over the best of seven legs. In the event of both nations winning one Singles match apiece, a best of seven legs Doubles match will be played to decide the tie.
Saturday's afternoon session will begin as 2013 finalists Belgium play Spain before 2012 runners-up Australia come up against Gibraltar.
Two-time champions England are in action during the evening session against Japan before host nation Germany take on Austria.
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2015 bwin World Cup of Darts
Friday June 12
Canada (11) 4-5 New Zealand
Sweden (15) 2-5 Hungary
Wales (7) 3-5 Hong Kong
Republic of Ireland (10) 5-0 Poland
Northern Ireland (6) 5-2 Thailand
Scotland (2) 5-1 Singapore
Netherlands (3) 5-2 United States of America
South Africa (14) 5-4 Finland
Saturday June 13
Afternoon Session (2pm local time, 1pm BST)
Belgium v Spain
Australia v Gibraltar
Northern Ireland v New Zealand
Hong Kong v Republic of Ireland
Evening Session (8.30pm local time, 7.30pm BST)
Scotland v Hungary
Netherlands v South Africa
England v Japan
Austria v Germany