World's best chess player loses tournament after 'horror mouseslip'

World Chess Champion Magnus Carlsen exited an online tournament on Thursday after accidentally moving his queen to the wrong square, allowing rival Hikaru Nakamura to take it with his king and ultimately win the match. Chess.com called the move a "horror mouseslip" for Carlsen, who left the event in third place with $15,000.

After beating Carlsen in that armageddon match (a special ruleset for tiebreakers), Nakamura went on to win the Chessable Masters tournament and its $30,000 top prize on Friday, putting him ahead of Carlsen in the rankings for this year's multi-event Champions Chess Tour. 

The result of Carlsen's fatal misclick can be seen in the screenshot above. At the top right of the board, Nakamura's king (black) can be seen capturing Carlsen's defenseless queen, which the Norwegian grandmaster had intended to move to b6 to take one of Nakamura's pawns. Instead, he stuck the piece on f6.

Apparently, this kind of thing happens enough that "mouseslip" is common Chess.com parlance. The commentators instantly knew what had happened after Carlsen reacted and then the move appeared on the stream.

"Magnus mouseslipped!" exclaimed caster Tania Sachdev. "Blundering into that queen! And Hikaru Nakamura takes this match!"

The tournament wasn't the biggest in the scheme of things, but it was notable for being Carlsen's last as the reigning World Champion, a title he's held since 2013 but has chosen not to defend.

"I simply feel that I don't have a lot to gain [from the World Chess Championship]," Carlsen said on his podcast last year. "I don't particularly like it, and although I'm sure a match would be interesting for historical reasons and all of that, I don't have any inclinations to play and I will simply not play the match."

Above: The error occurs at around 3:30:00. Carlsen reacts before the slip is displayed.

Carlsen was all over the news last year after he and others, including Chess.com itself, accused grandmaster Hans Niemann of cheating, which Niemann responded to with a lawsuit. 

With Carlsen vacating his throne, the next World Chess Champion will either be Ian Nepomniachtchi or Ding Liren, who are now competing for the title in Astana, Kazakhstan.

As this week's loss indicates, Carlsen isn't retired from chess just because he's through being World Champ. The Champions Chess Tour he's participating in includes several more events this year and will culminate in a series of playoffs and finals with a $500,000 total purse, for instance.

This may, however, be the only time we at PC Gamer are ever able to give the world's best chess player advice on playing chess, so Magnus, if you need help picking a gaming mouse with a firmer clicking mechanism, hit us up.