Once it was determined to be a legitimate move, the general reaction was, Chamley-Watson said: “Wow, he hit you in your chest by wrapping his own arm around his own head.”

Besides being showstopping, the move can be startlingly effective.

“It’s really hard to defend,” Chamley-Watson said. “I can hit you in the upper part of your torso, the lower part of your torso — even on your back, if you duck. So it’s a very effective move, and it’s nice that I’m the only one who can do it.”

That’s one reason that other top fencers have not quickly adopted the move: They just can’t do it. Chamley-Watson is helped by standing 6 feet 4. “I’m very flexible, and I have very long arms,” he said. “I don’t think you could do it if your arms are short.”

Massialas said: “Nobody is as tall or lanky or as quick as he is.”

Few fencers are happy to be the victim of the splashy move. Some take drastic steps to avoid being shown up by it.

“They get super-embarrassed,” Chamley-Watson said. “That’s the best part. Everyone gets super-mad.

“They always try to block it. They’ll take a yellow card, they’ll try to bump into me. They’d rather get a yellow card than get embarrassed on live television.

“I don’t blame them.”

Chamley-Watson was born in London, came to the United States at age 9 and eventually fenced at Penn State. At the 2012 Olympics, he was a medal contender but was surprised by Alaaeldin Abouelkassem of Egypt in the second round.