Michael van Gerwen was dumped out of the Ladbrokes Masters by Jonny Clayton for a second successive year in Milton Keynes on Saturday.
Five-time Masters champion Van Gerwen saw his 20-match unbeaten run in the tournament ended by Clayton in last year's event, and the Welshman repeated the feat with a 10-9 victory at the Marshall Arena.
Having suffered a humbling defeat to Dave Chisnall at the World Championship and subsequently losing his world number one status, Van Gerwen was out to bounce back with a sixth Masters crown but soon found himself 4-1 down in their last 16 clash.
The Dutchman landed trademark checkouts of 158, 150 and 148 as he battled his way to a last-leg decider, but back-to-back 180s from Clayton relieved the pressure on the World Cup winner who closed out victory in 14 darts.
"I got out of the blocks fast and I think that helped, I could see Michael shaking his head early on," Clayton explained.
"It's always tough in a last-leg decider against one of the best players ever to have played the game, and those two 180s couldn't have come at a better time. I was even thinking about a nine-darter!
"Hopefully I can go all the way, that's what I'm out to try and do. Let's see what happens tomorrow."
Clayton will take on James Wade in Sunday's quarter-finals after the 2014 champion brushed aside Chris Dobey 10-4 in a typically clinical display of finishing.
The second day of the first televised event of 2021 saw eight second round matches take place, with Friday's first round winners returning to the stage to face the eight seeded players.
Adrian Lewis was among the round one winners and he continued his return to form with an impressive 10-8 win over Gary Anderson to reach his first TV quarter-final since July.
Having come through a deciding leg against Michael Smith in round one, 2013 Masters runner-up Lewis averaged 98.56 with a 50% checkout success rate to maintain his positive start to 2021.
"I'm over the moon to win against Gary," said Lewis. "He's just been in a World Championship final so he's in good form.
"I feel like I'm in the mix again, for the last three or four years I felt like I was out of it. I've always said it only ever takes one tournament to get back to your best.
"I know what I'm capable of and what I'm showing here is a lot more like it, but I still know I can do a lot better."
Next up for Lewis is a meeting with World Champion and world number one Gerwyn Price who picked up where he left off at Alexandra Palace with a 104.37 average in a resounding 10-3 defeat of Joe Cullen.
There were no signs of pressure on the shoulders of Price who embraced his new titles, hitting five 180s and a 132 checkout to reach the quarter-finals for a third time, though the Welshman is yet to make it beyond that stage.
"It was nice to be called out as World Champion for the first time," said Price. "Obviously it would've been better with a crowd in but it was good, I enjoyed it.
"I was expecting Joe to fire a bit more at me, I felt comfortable throughout the game.
"I wanted to start my reign as World Champion off on a positive note and I'm happy to have done that tonight."
Reigning champion Peter Wright began his title defence with a 10-8 victory over Simon Whitlock, defying a 105.9 average from his Australian opponent.
Having gone 3-2 up Wright maintained a narrow lead throughout, and after Whitlock missed two darts to force a deciding leg, the former World Champion found double 16 with his last dart to get over the finish line.
"I'm pleased with the win, Simon's a fantastic player who has been playing some superb darts recently," said Wright.
"I've been on the practice board since the day I lost at the World Championship. I've decided I want to play serious darts this year.
"This is a brand new tournament. Just because I won it last year is irrelevant, I've got to go back out there tomorrow and perform if I'm going to retain this title."
Chisnall lays in wait for Wright after the 2016 runner-up came through a last-leg shoot-out to defeat Daryl Gurney 10-9, having surrendered a 6-3 advantage.
A typically resilient display from Gurney saw him land a 170 checkout on his way to forcing a decider, though he was never allowed a match dart as Chisnall pinned double nine with his last dart for a match-winning 74 checkout.
Nathan Aspinall also came through a last-leg decider against Mensur Suljovic, recovering from 9-7 down and surviving five match darts to secure a much-needed victory in dramatic fashion.
Having suffered early exits in his last two televised outings, Aspinall looked in danger of a repeat before Suljovic missed two darts to win 10-7.
Aspinall took full advantage to send the match to a dramatic deciding leg, and after Suljovic missed three clear darts at double, he made no mistake on double ten to book his place in the last eight.
"I felt I played really well, even though the stats might not back that up," said Aspinall.
"Luckily for me Mensur missed, I couldn't believe he missed to be honest. But when you get a bit of luck you've got to pounce on it and I managed to do that.
"Losing would've been the worst possible start to what will be a big year for me, so I'm relieved to be through."
Aspinall will meet a resurgent Mervyn King after the 2014 runner-up secured a comprehensive 10-5 defeat of Rob Cross, averaging 101.64 to maintain his impressive form.
The Ladbrokes Masters concludes on Sunday with the quarter-finals in the afternoon session, followed by the semi-finals and final in the evening.
Worldwide coverage will be led by host broadcaster ITV4 in the UK and Ireland, as well as through RTL7 in the Netherlands and DAZN in various global territories, as well as through the PDC's global broadcasters, for PDCTV Rest of the World Subscribers and through matchroom.live.
2021 Ladbrokes Masters
Saturday January 30
Second Round x4
Mervyn King 10-5 Rob Cross
James Wade 10-4 Chris Dobey
Nathan Aspinall 10-9 Mensur Suljovic
Dave Chisnall 10-9 Daryl Gurney
Second Round x4
Adrian Lewis 10-8 Gary Anderson
Peter Wright 10-8 Simon Whitlock
Gerwyn Price 10-3 Joe Cullen
Jonny Clayton 10-9 Michael van Gerwen
Sunday January 31
Afternoon Session (1245 GMT)
Mervyn King v Nathan Aspinall
Gerwyn Price v Adrian Lewis
Peter Wright v Dave Chisnall
Jonny Clayton v James Wade
Evening Session (1900 GMT)
Price/Lewis v King/Aspinall
Clayton/Wade v Wright/Chisnall