Not long ago, an anonymous YouTuber known only as Quash Bad Squash reposted one of the strangest moments in the history of the sport.

It’s match ball in the finals of last year’s British Open tournament, with a check for $26,600 on the line. The four-time world champion Ali Farag, an Egyptian with the physique of a pipe cleaner and the speed of Mercury, is about to lunge forward and hit a backhand. But as he tries to get past his opponent, a rising superstar and fellow countryman named Mostafa Asal, Mr. Farag does something baffling.

He stops playing.

Instead, he wheels around to look at Mr. Asal, as if he’s momentarily stunned.

“Oh, my goodness gracious me!” shouts one of the commentators broadcasting live on the website SquashTV.

“What has he done?” shouts another.

The referee isn’t sure. So a second referee, whose job is to handle tough calls, looks at instant replay video footage to determine if Mr. Asal blocked his opponent — a no-no that would cost him the point. The second referee watches the sequence a few times and sees nothing wrong.

Point and match to Mr. Asal. He buries his face in his hands, overwhelmed with joy.

For everyone else, a mystery remained: Why did Mr. Farag stop playing?