An upset needs two things: a heavy favourite and a result nobody had modelled. That second part is why the list below is shorter than most. Beating a first seed is not an upset if the region was in decline that year, and a five-game series between two evenly matched sides is a good series rather than a shock.
These four clear the bar. Each one removed a team that was expected to win the tournament.
1. DRX, Worlds 2022
DRX did not look like a Worlds team in September and won the whole thing in November. They arrived as the LCK's fourth seed, through the regional qualifier.
They went undefeated through the play-in stage, then topped their group at 4-2 on a tiebreaker against Rogue. That set up a quarter-final against EDward Gaming, the defending world champions. DRX lost the first two games, including one where EDG's inhibitor respawned with a single auto-attack from ending it. They won the next three. It was the second reverse sweep in the history of the tournament.
