Raymond van Barneveld rolled back the years to earn a breathtaking 4-3 victory over World No.1 and World championship favourite Michael van Gerwen at the Alexandra Palace to move into the quarter-finals.
The pendulum swung back and forth between the two Dutchmen but it was 48-year-old Barney, a five-time World champion, who clinched a remarkable victory to earn the right to face Michael Smith in the last eight.
It was 2014 champion Van Gerwen who struck the first blow by clinching the first leg 3-1, but Barney hit back to claim the second leg on the same scoreline to level matters at one set apiece.
The duo proved hard to separate in the third set and traded blows before Van Barneveld gained the upper hand to lead the match.
Going behind spurred Van Gerwen on, however, and he clinched a maximum 170 checkout as he took the next set in straight legs to level the scores once again.
Barney then showed why he is worth a wild card in next year's Premier League with a classy 180 before checking out on 124, and he followed it up in the next leg as the pendulum swung back in his favour with a 3-2 lead.
But Van Gerwen held his nerve to hold his throw at 2-2 in the next set to ensure the tie went to a deciding set.
It was in vain, however, as Van Barneveld kept his cool to clinch the upset of the tournament so far.
He will now face Smith, who put in a spectacular performance in yesterday's afternoon session to reach the quarter-finals for the first time.
The former PDC Unicorn World Youth Champion hit 12 180s in just 16 legs as he saw off Holland's Benito van de Pas in straight sets.
Smith, the No.8 seed, said: "That performance has made me stronger in this tournament.
"I had fun up there and that made me play better. In the next game I'll have even more fun because I won't be the favourite so I can relax and play without pressure."
Defending champion Gary Anderson fired out a warning as he reached the last eight with a 4-0 win over Vincent van der Voort.
The World No.2 only dropped one leg during the rout and will next face James Wade
Wade, a three-time semi-finalist, earned a 4-1 success over Jamie Caven despite feeling under the weather.
"I think everyone has got a bit of a cold and I'm not feeling great so I'm pleased with how it went," said Wade.
Two-time World champion Adrian Lewis got yesterday's evening session under way with a comprehensive 4-0 defeat of Mensur Suljovic.
Jelle Klaasen defeated Mervyn King in the final match of round two yesterday afternoon. The Dutchman took out a brilliant 170 finish on the way to a 4-2 triumph and will face Phil Taylor tonight for a place in the quarter-finals.