Two-time champion Adrian Lewis was stunned 3-1 by German qualifier Kevin Munch in the first round of the PDC World Championship at Alexandra Palace.
Lewis won the first set but Munch hit back with a series of high checkouts, winning the third set in straight legs.
Munch, who beat Aleksandr Oreshkin in the preliminary round on Tuesday, ended with eight 180s to secure a major upset against the English seventh seed.
Five-time champion Raymond van Barneveld eased through to round two.
The Dutchman averaged 102 as he saw off debutant Richard North in straight sets.
Elsewhere, Scotland's John Henderson claimed a 3-0 victory over Finland's Marko Kantele.
Munch monsters Jackpot
Lewis, the 2011 and 2012 champion, had never previously lost in the first round of the World Championship.
The 32-year-old looked set to extend that record as he took the first set 3-1, before moving into a 2-0 lead in the second set.
But Munch, 29, reeled off three consecutive legs to draw level before hitting a 158 checkout to move 2-0 in front in the third set.
More heavy scoring saw the German clinch that set and a 124 checkout put him a leg away from victory in the fourth.
'Jackpot' Lewis fought back to level the set at 2-2 but Munch finally sealed victory by hitting double eight.
It was a second shock in as many days at Alexandra Palace, after veteran qualifier Paul Lim upset Mark Webster on Monday.