Van Duijvenbode boosted his hopes of a World Matchplay return with a statement win over Price at the Ostermann-Arena, reeling off five consecutive legs from 2-1 down to avenge his defeat in last year’s final.
The 2023 runner-up averaged 102 and pinned six of his nine attempts at double to topple the Welshman, having also hit six of his seven attempts in Friday’s first round win against Gabriel Clemens.
“My confidence is not there yet, but I feel like I’m getting back to where I used to be,” declared Van Duijvenbode, who has been battling injury problems throughout the last 12 months.
“I had a nine-darter in practice yesterday, today I hit two in 30 minutes in practice. I’ve never done that in my life and now I’ve hit three in 24 hours!
“I feel determined to show people that Dirk is not done. I feel like I’m getting closer, but I’m not done, I promise you!”
Saturday’s second round took place across a double session of action, with world number one Humphries also crashing out following a 6-4 defeat against 2012 champion Van Barneveld.
The five-time World Champion produced five 180s and defied a brace of ton-plus finishes from the top seed to progress to the last 16 of a European Tour event for the first time in 2024.
“To beat the world number one is an amazing feeling,” reflected Van Barneveld, who will play his compatriot Gian van Veen for a place in the quarter-finals.
“Luke is an amazing player. When you’re the World Champion, you have a target on your back, but Luke doesn’t deserve that. He’s a fantastic guy and we’re good friends.
“I keep believing in myself. I feel relaxed, and when you’re relaxed, you can achieve anything.”
Elsewhere, Michael van Gerwen joined his fellow countrymen in Sunday’s last 16, after kicking off his bid for a record-extending sixth European Darts Open crown with a battling 6-4 success against Dylan Slevin.
German number one Martin Schindler preserved home hopes with a 6-4 victory over Karel Sedlacek, averaging 102 and landing a brace of ton-plus finishes to book a last 16 tussle against Van Duijvenbode.
Michael Smith completed a whitewash win against an out-of-sorts Rob Cross to set up a meeting against Peter Wright, who won five straight legs in overturning a 3-1 deficit against Ritchie Edhouse.
Josh Rock produced a ton-topping average to open his challenge for a second straight European Tour title, taking out a spectacular 160 checkout to wrap up a 6-3 win against Dimitri Van den Bergh.
Having opened his European Tour account with victory against Joe Cullen on Friday, Owen Bates continued his breakthrough run in Leverkusen, recovering from 5-3 down to stun sixth seed Danny Noppert.
Earlier in the day, second seed Dave Chisnall also hit back from 5-3 down to sink Luke Woodhouse, surviving a match dart in the penultimate leg in a contest which saw both players average over 100.
Chris Dobey also survived match darts in his dramatic last-leg victory against Jeffrey de Graaf, as Masters champion Stephen Bunting won through a scrappy affair against Host Nation Qualifier Kevin Troppmann.
Kevin Doets landed five 180s to fend off a late fightback from Ricardo Pietreczko and move into the provisional World Matchplay qualification places, overhauling ten-time TV title winner James Wade in the process.
Doets’ fellow Dutchman Van Veen won a topsy-turvy contest against Lakeside champion Andy Baetens, who fought back from 4-0 down to level, before Van Veen regained his poise to progress.
Damon Heta prevailed in a high-quality affair against Dom Taylor, averaging 99.99 and pinning six of his 12 attempts at double to cap off a clinical 6-4 success.
Ryan Searle overcame Daryl Gurney by the same scoreline to create a third round meeting against five-time winner Van Gerwen, while Ross Smith brushed aside a below-par Callan Rydz in his opener.
The third round of the NEO.bet European Darts Open will take place on Sunday afternoon, before the tournament concludes with the quarter-finals, semi-finals and final in a bumper evening session at the Ostermann-Arena.
Saturday June 22
Second Round
Afternoon Session
Evening Session
Sunday June 23
Afternoon Session
Last 16
Evening Session (1900 local time, 1800 BST)
Quarter-Finals
Semi-Finals
Final