How it unfolded
The 23-year-old Keith Deller entered this tournament as a qualifier ranked outside the world's top 30. On his way to the final he beat former world champions Jocky Wilson and John Lowe, and his final opponent was Eric Bristow, already a two-time world champion and the overwhelming favourite that year. The match went the distance, tied 5-5 into the deciding set. On the decisive leg, Bristow, with 121 remaining, chose to leave 50 rather than attempt a bullseye finish with his last dart, judging that Deller's chance of checking out 138 with three darts was low. Deller hit treble 20, treble 18, then finished on double 12 to check out 138. The winner's cheque was larger than any sum he had ever earned, and the nickname "the Milky Bar Kid," given for his resemblance to a boy in a milk advert, followed him for the rest of his career.
Why it still matters
This is darts' most famous upset, and the moment that best compressed what this sport actually is into a single scene: nothing the opponent does can be touched, and in the end all that is left is your own three darts. That truth was proven by a single 138 checkout. Bristow's choice is still cited today as the counter-example when explaining checkout strategy, and Deller's finish remains one of the most replayed pieces of footage in the sport.