World chess champion Magnus Carlsen accidentally moved his queen to the wrong square in an online tournament on Thursday, losing out to rival Hikaru Nakamura, who took the queen with the king and ultimately won the tournament. Chess.com called Carlsen a " fearful mouse-slip" and left the tournament in third place, winning $15,000.

Nakamura, who defeated Carlsen in that Armageddon match (open in new tab) (a special rule set for tiebreakers), won the Chessable Masters tournament and its $30,000 prize money on Friday and is ranked in this year's multiple Champions Chess Tour. He surpassed Carlsen.

The result of Carlsen's fatal missed click can be seen in the screenshot above. In the upper right corner of the board, Nakamura's king (black) can be seen catching a defenseless Carlsen's queen. 5]

Apparently, this happens so often that "mouse slip" is a common Chess.com phrase. Commentators knew instantly what had happened because their hands appeared in the stream after Carlsen responded.

"Magnus has a mouse slip!" shouted caster Tania Sakdev, "Magnus has a mouse slip! Magnus has had a micelip!" shouted caster Tania Sachdev! And the match went to Hikaru Nakamura.

The tournament was not a big one, but it is worth noting that it was Carlsen's last tournament as world champion, a title he has held since 2013.

"I simply feel that I have little to gain [from the World Chess Championship]," Carlsen said last year on his podcast (open in new tab). 'I don't particularly like it, and I'm sure the matches will be interesting for historical reasons and all that, but I'm not going to play them, I simply won't play them.'

Above: the mistake occurred around 3:30:00. Carlsen reacts before the slip is shown.

Carlsen made headlines last year when he and others, including Chess.com itself, accused Grandmaster Hans Niemann of cheating and Niemann filed suit against them.

With Carlsen vacating his title, the next world chess champion will be either Ian Nepomniacki or Dinglen, who is currently competing for the title in Astana, Kazakhstan.

As this week's loss shows, Carlsen did not retire from chess just because he became world champion. The Champions Chess Tour, of which he is a member, has several events this year, culminating, for example, in a playoff and final with a prize pool of $500,000.

But this may be the only time we at PC Gamer can advise the world's best chess players on how to play chess.