Nathan Aspinall's reign as Betfred World Matchplay champion was brought to an end by James Wade on Tuesday in Blackpool, while Luke Humphries, Dimitri Van den Bergh and Ross Smith also advanced to the quarter-finals.
Wade battled his way to an 11-8 victory over Aspinall, coming out on top in a scrap between two of the sport's most stubborn competitors.
Wade raced into a 4-0 lead before Aspinall fought back, once again playing through the pain of an arm injury, to lead 8-7.
However, Wade finished stronger, winning the last four legs without reply to book his place in the last eight for the first time in five years.
"Nathan didn't play how he can so I'm a lucky boy tonight," said Wade, who is making his 19th consecutive World Matchplay appearance.
"But the main thing is I'm through and I'm happy to still be in the tournament.
"I've got nothing to prove; no one has won as many tournament as me apart from Michael [van Gerwen] and Phil [Taylor]."
Wade will meet Ross Smith in the quarter-finals, after Smith broke new ground with a hard-fought 11-9 win over Gerwyn Price.
Both players got off to a slow start before a captivating contest ensued, with Price nudging ahead at 8-6.
Smith then found top gear, winning five of the last six legs to earn a maiden World Matchplay quarter-final berth.
"It means everything to me to be in the quarter-finals," said Smith. "I used to watch this tournament as a kid and I've worked really hard to get here.
"In the first part of the game neither of us were at the races, so I was trying to fire myself up.
"I kept telling myself to fight, I dug deep and got on with it.
"I've had a tough draw as well against Gerwyn and Josh [Rock] so that makes it even more satisfying."
World number one Humphries continued his bid for a first World Matchplay title with an 11-7 victory over Stephen Bunting.
Humphries impressed with a 102.34 average, though he had to recover from 6-5 down to defeat a determined Bunting.
The World Champion finished strongly, winning six of the last seven legs to book his place in the last eight for a second successive year.
"I didn't have it all my own way," said Humphries, a semi-finalist last year. "Stephen is a battler and he put me under pressure in every leg.
"He's a lovely man and I can see why he gets so much support.
"It was a fantastic game of darts, it always is when we play each other.
"I know I can win it, I've won the biggest tournament in the world, it's not going to be easy but I'm ready to fight for this title."
Humphries will face Van den Bergh in the quarter-finals, after he avenged last year's loss to Jonny Clayton.
2020 champion Van den Bergh landed a pivotal 112 checkout to go 8-5 up on Clayton, who defeated the Belgian at the same stage of last year's event.
From there, Van den Bergh won the last three legs to reach the last eight for the fourth time in five years.
"I'm exhausted," admitted Van den Bergh. "I tried my hardest and I never gave up.
"I hit some big shots under pressure, I never thought I would beat Jonny 11-5 in this format, he is an amazing player.
"It's not about who's in front of me, it's about what I need to do to get the best out of myself."
The second round action at the Betfred World Matchplay continues on Wednesday night as three-time champion Michael van Gerwen takes on Joe Cullen.
2019 champion Rob Cross meets Ryan Searle, world number three Michael Smith faces Chris Dobey, while Krzysztof Ratajski and Andrew Gilding open the night.
The Betfred World Matchplay is broadcast live on Sky Sports in the UK, through the PDC's worldwide broadcast partners including DAZN and Viaplay, and on PDCTV (excluding UK, Germany, Austria & Switzerland based subscribers).
2024 Betfred World Matchplay
Tuesday July 16
4x Second Round
Ross Smith 11-9 Gerwyn Price
James Wade 11-8 Nathan Aspinall
Luke Humphries 11-7 Stephen Bunting
Dimitri Van den Bergh 11-5 Jonny Clayton