Australia battled their way to a 2-1 win over Wales thanks to some clinical double-hitting.
Simon Whitlock got off to a blistering start in his 4-2 win over Gerwyn Price in the opening game, firing in five 180s to give Australia the advantage.
Jonny Clayton hit back to keep Wales in the tournament with an impressive 4-0 whitewash of Kyle Anderson to take the match to a doubles decider.
Wales took the first leg in the Pairs, before Anderson hit a crucial double 18 with his last dart in hand to level.
Anderson continued hic clinical doubling, hitting three more winning doubles including a 121 on the bullseye to secure Australia’s place in the final four.
“We help each other out when we’re not at our best, we play as a team,” said Whitlock.
“It was nice to hit the 180s but the main thing is to get through to the next round and then go all the way.”
Scotland became the first team to book their place in the quarter-finals with a comfortable 2-0 win over surprise package Japan without dropping a single leg.
Peter Wright kicked off the afternoon session with a clinical 4-0 rout of Seigo Asada, hitting two bullseye finishes along the way.
Gary Anderson backed up Wright’s win with another whitewash, this time against Haruki Muramatsu as the two-time World Champion pinned a 110 finish en route to victory and set up a clash with Australia in the final four.
“It was pleasing to get the win in comfortable fashion,” said Wright.
“I was happy with my two bull finishes and hopefully I can throw a few more tonight and we can go all the way.”
The Netherlands silenced the Frankfurt crowd with a comfortable 2-0 victory over Germany in a repeat of last year’s quarter-final.
Michael van Gerwen had to be at his best as he defeated Martin Schindler 4-1 in the opener, despite the young German averaging 110.
Raymond van Barneveld sealed the deal for the Dutchmen with a 4-0 whitewash of Max Hopp to continue their quest for back-to-back World Cup titles.
“I think we played a phenomenal game and we’re happy to be through,” said Van Gerwen.
“The semi-final against Belgium will not be easy because their team is stronger than previously, Dimitri is a top player but we are very confident.”
Belgium produced a fine display to dump four-time winners England out of the tournament with a 2-1 win.
Rob Cross posted a world-class 107.48 average in the opening Singles game as he beat Kim Huybrechts 4-2 to put England in the driving seat.
Dimitri Van den Bergh struck back for Belgium, breaking the Dave Chisnall throw in the final leg to win 4-3 and force a Pairs game.
The Belgian pair produced a superb doubles display, limiting England to just one dart at double in the match to record a 4-0 whitewash and progress to their semi-finals for a second consecutive year where they will face the Netherlands.
“That was one of my best feelings in darts,” said Huybrechts.