Day Nine of the £2.5 million event saw the final eight second round matches take place at Alexandra Palace, with Grand Slam of Darts champion Price surrendering a 2-0 lead to former World Youth Champion Aspinall.
The opening two sets both went to last leg deciders, with Price edging both 3-2 to take a commanding 2-0 lead.
Set three also went the full five legs, but after Price missed the bullseye for a 3-0 victory, ProTour event winner Aspinall hit double 16 with his last dart in hand to get his first set on the board.
Growing in confidence, Aspinall hit a 140 checkout to take the third set 3-1, and then took the lead for the first time since the opening leg to go 1-0 up in the deciding set before reeling off the last two legs to secure a famous win.
“This is absolutely massive for me and my family, and I’m not done yet,” said Aspinall, who will take on Kyle Anderson in round three.
“I know what I can do and I knew if I played my game I could win, even at 2-0 down I thought I would still win and I never gave up.
“Going full-time this year was a big risk for me and my family, but winning a ProTour event along with this win tonight gives me security and I couldn’t be happier.”
A strong performance from Anderson saw him come through a tough test against Noel Malicdem, defeating the Filipino qualifier 3-1 in another high-quality affair.
A sensational comeback from Petersen saw him come back from two sets down to defeat 11th seed White 3-2 after a tense tie-break.
White, a winner of three PDC titles in 2018, got off to a flying start as he took the opening two sets for the loss of just one leg with an average of over 110.
However, a dramatic turn of events saw South African Qualifier Petersen, starring in his sixth World Championship, rattle in five 180s to win both the third and fourth sets 3-1 to take the match to a deciding set.
The pair exchanged breaks of throw, followed by two holds to take the contest to a tie-break before Petersen struck a crucial break to go 4-3 up, and then found double ten with his second match dart to clinch the victory.
“This is the biggest win of my life, I couldn’t be happier right now,” said Petersen, who will face Steve West in round three.
“I love playing on the Ally Pally stage, it’s a magnificent showcase for me to show my best game and to show people what I’m all about.
“Over the last 18 months I’ve been adapting my throwing style, which is why I haven’t had great results on the tour, but I’m glad that my best game is coming through now when it matters most.”
Meanwhile, superior finishing proved to be the difference for West as he ran out a 3-1 winner over Richard North.
Dimitri Van den Bergh produced the highest winning average of the tournament (104.45) in his impressive 3-1 triumph over Jonny Clayton.
Last year’s quarter-finalist Van den Bergh got off to a flying start, winning the opening leg 3-0 with three 13-dart legs, before Clayton fired in three 180s on his way to winning the second set 3-1 to level the contest.
Van den Bergh took set three 3-1, and then came back from 2-0 down in the fourth set, kick-started by a 108 finish, to reel off three successive legs for the win and set up a meeting with Luke Humphries.
“I am so happy with how I played tonight but I know this is how I need to play if I’m going to become World Champion,” said back-to-back World Youth Champion Van den Bergh.
“I wasn’t feeling comfortable in myself in my first round game but since then I spent a lot of hours on the practice board with my dad which gave me the perfect preparation to produce this performance.”
The opening game of the day saw Benito van de Pas survive a match dart before defeating Jim Long 3-2 in a dramatic tie-break.
Competing in his fifth consecutive World Championship, Van de Pas took the opening two sets with the concession of just two legs, only for Canadian Qualifier Long to fight back with two sets of his own to take the match to a deciding set.
With nothing to separate the pair at 2-2 in the fifth set, the game went to a tie-break with Long missing a dart at tops for the match at 3-2.
Van de Pas fought back with three successive legs, winning it with a stunning 150 finish and he will now face Spain’s Toni Alcinas.
John Henderson came through a high-quality five-set contest with Gabriel Clemens to set up a meeting with Michael Smith, while former World Youth Champion Keegan Brown will take on James Wade in a rematch of last year’s first round after coming from a set down to defeat former semi-finalist Jelle Klaasen 3-1.
The action continues on Saturday with six third round ties, featuring two-time World Champions Michael van Gerwen and Gary Anderson.
The tournament will be broadcast live on the dedicated Sky Sports Darts channel from December 13-January 1 and worldwide through the PDC’s international broadcast partners.
2018/2019 William Hill World Darts Championship
Schedule of Play
Friday, December 21
Benito van de Pas 3-2 Jim Long (R2)
John Henderson 3-2 Gabriel Clemens (R2)
Steve West 3-1 Richard North (R2)
Kyle Anderson 3-1 Noel Malicdem (R2)
Devon Petersen 3-2 Ian White (R2)
Keegan Brown 3-1 Jelle Klaasen (R2)
Nathan Aspinall 3-2 Gerwyn Price (R2)
Dimitri Van den Bergh 3-1 Jonny Clayton (R2)
Saturday, December 22
Afternoon Session (1230)
Ryan Joyce v Alan Norris (R3)
Dave Chisnall v Kim Huybrechts (R3)
Daryl Gurney v Jamie Lewis (R3)
Evening Session (1900)
Ryan Searle v William O’Connor (R3)
Gary Anderson v Jermaine Wattimena (R3)
Michael van Gerwen v Max Hopp (R3)