Van Gerwen crashes out of World Matchplay
Two-time World Matchplay champion Van Gerwen failed to make it past round two for a third successive year, as Whitlock claimed his first win over the world number one since 2016 at the Marshall Arena.
Van Gerwen had won the previous 15 meetings between the pair, but Whitlock took full advantage of the Dutchman's below-par performance to cause the biggest upset of the tournament so far.
"I'm over the moon with that, but I always believe I can beat the best," said Whitlock. "Michael is the best player on the planet but he had an off-day today and I took advantage of it.
"I just put Michael out of the picture and pretended I was playing local darts. I believed in myself and that's the only way to do it. If you play the player you will put yourself in trouble.
"Experience counts for that, and along with a love for the game, that's what keeps us older players going."
Van Gerwen, who follows world number three Gerwyn Price and reigning World Matchplay champion Rob Cross in early exits from the tournament, got off to the worst possible start to trail 5-0.
A rampant Whitlock never allowed his opponent within three legs, as the Australian number one punished Van Gerwen's 20 missed doubles from 24 attempts at the outer ring.
With the three-time World Champion unable to mount a fight back, Whitlock pinned double nine to seal a surprisingly comfortable victory.
Whitlock will now face Gary Anderson in the last 16, after the Scot ran out an 11-8 victory over James Wade in the battle of the former World Matchplay champions.
2018 winner Anderson, who is now the only player left in the field to have lifted the title, threw nine 180s and twice threatened a nine-dart finish by opening the ninth and tenth legs with six perfect darts.
From 3-2 down, Anderson won seven of the next eight legs to move into a commanding 9-4 lead, taking advantage of some uncharacteristic missed double attempts from Wade.
A hat-trick of legs saw Wade fight back to trail 9-7, but Anderson twice found his favourite double top to end hopes of a fightback.
2019 runner-up Michael Smith became the first player to reach the quarter-finals, coming through a dramatic tie-break with Mensur Suljovic to win 14-12.
Smith, who piled in ten 180s, recovered from deficits of 8-5 and 9-6 to take Suljovic to a second tie-break in as many matches.
The opening four legs of the tie-break were shared, with neither player crafting out a match dart, before Smith struck a vital break of throw to go 13-12 up.
After Suljovic spurned three double attempts to break straight back, Smith landed a timely 110 checkout to book a last eight meeting with Krzysztof Ratajski.
Polish number one Ratajski battled his way to a 12-10 victory over Germany's Gabriel Clemens.Clemens, who defeated Cross in round one, hit nine 180s but trailed from the first leg of the match until the 18th, when a crucial break of throw saw him tie up the contest at 9-9.
The German number two then hit the front with an 85 finish to hit the front for the first time, only for Ratajski to win a trio of legs to book his place in the quarter-finals on his second World Matchplay appearance.
The night also saw the first round draw to a close, as World Matchplay debutant Dimitri Van den Bergh enjoyed a surprise 10-6 win against Nathan Aspinall.
A hat-trick of 13-dart legs from Van den Bergh helped the Belgian take a firm grip of the game to lead 6-2, before finishes of 103 and a stunning 156 kept the lead out of Aspinall's reach.
Unable to mount a comeback, Aspinall was condemned to back-to-back first round defeats in his first two World Matchplay outings, as Van den Bergh avenged his 2019/20 World Championship loss.
The second round concludes on Wednesday's Night Five, as 2017 runner-up Peter Wright takes on Glen Durrant in the pick of the ties.