Ken Yukuhiro was disqualified in Round 14 of the 2018 Magic: The Gathering World Championship.

In Game 1, Yukuhiro drew a Diamond Mare that should have been in his sideboard. He did not bring this to the attention of the judges when he noticed that he had failed to de-sideboard from the previous round. A judge was observing the game and recognized that the card was from Yukuhiro's sideboard. After a turn had passed, Yukuhiro called a judge regarding his failure to de-sideboard.

As the judge had observed the game and had witnessed the sideboard card not being brought to an official’s attention upon it being drawn, an investigation was conducted. At its conclusion, Yukuhiro was disqualified.