For the country that invented judo, winning only one gold medal at last year's London Olympics was like a humiliating flip onto its back.
But Japan has now been given a fighting chance at reclaiming its dominance after judo's ruling body changed the rules to promote a classic style that goes back to the sport's ancient samurai origins. At this week's world championships in Rio de Janeiro, the Japanese have already racked up three gold medals and are sitting on top of the medals table.
"The new rules make judo more traditional and that definitely favors the Japanese," said Jimmy Pedro, a U.S. Olympic coach and former world champion.
There are two main ways to win at judo: Throw your opponent to the ground so they land flat on their back or pin them to the ground until they submit, or for 20 seconds.
Japanese judoka typically focus on the martial art's tradition of fighting while standing and throwing their opponents for an automatic victory. Judo players around the world who lack classic Japanese training often compensate by using strong grappling techniques that are less elegant but still effective.
The new judo rules include changes that emphasize the sport's standing techniques and outlaw direct attacks on the opponent's legs, often used in countries with a strong wrestling background like Russia, which won the most gold medals in London. So far in Rio, Russia has only one bronze medal.
"You used to be able to beat the Japanese with some unorthodox gripping and with leg attacks, things they're not used to," Pedro said. "But now you have to retrain yourself not to do those things or you risk disqualification."
The International Judo Federation says the rules were changed to make judo more dynamic, not to help Japan win more medals.
"All countries which are promoting dynamic and spectacular judo based on (an attacking style) are doing well in Rio," Nicolas Messner, an IJF spokesman, said in an email.
He said Japanese judoka were specialists in traditional judo but that other countries are also capable of producing champions.
Still, Japan may be more motivated than others.
Masashi Ebinuma, who won his second world title on Tuesday, said he wasn't even focused on that goal this week.
"I wanted to make amends for my Olympic result," he said, referring to his bronze medal in London.
The 2012 Games were the first Olympics since judo was introduced when the Japanese men were shut out of the gold medals.
"The Japanese are loving the new rules and they're having a great run at the championships," said Neil Adams, an advisor for the new rules and a two-time Olympic medalist from Britain. "Judo now looks like we think it should look, with lots of big throws and less wrestling."
American champion Kayla Harrison who won the U.S. team's first-ever judo gold at the 2012 Games, said she was torn over the changes, saying they helped separate judo from other sports but wasn't sure they made it more exciting to watch.
"A lot of moves that were once part of judo have now been eliminated. You used to see people pick someone up mid-air, grab their legs and the next thing you know, someone's on the ground," she said. "It's definitely not like that anymore."
Though Harrison doesn't usually favor classic judo techniques, she will tweak her training program once she's back on the mat; she's currently sidelined with a knee injury.
"I think I'm going to be putting in a lot of time in Japan," she said.