LONDON (AP) — When the judo events kick off at the Rio de Janeiro games, the home team will send out a defending Olympic champion on the first day of competition.

With five other top-ranked judoka on its Olympic team, Brazil has a particularly strong home advantage. Although judo has traditionally been dominated by the Japanese, who created the modern martial art, the combat sport has become truly universal. That means the Japanese team, which won only a single gold medal at London in its worst-ever Olympic showing — is no longer the favorite.

Marius Vizer, president of the International Judo Federation, said he expects to see more unexpected winners at Rio.

"I think Mongolia will be the big surprise of the Olympic games," he said. Vizer also noted strong fighters from the U.S., Greece, Georgia, France, Russia, Cuba and South Korea. There will also be two refugee competitors, from the Democratic Republic of the Congo, competing under the International Olympic Committee flag.

Vizer said some rule changes to judo — including the outlawing of leg grabs — were made to distinguish the sport from others like wrestling and will hopefully inspire more fighters to attempt the big throws judo is known for. Fights can be won instantly if judoka flip their opponents flat on their back "with considerable force and speed."

While some have criticized the rule changes arguing that they favor the Japanese style of judo, which focuses on throws rather than the groundwork component of judo, Vizer said the tweaks are necessary to modernize the sport.

Countries with a strong wrestling tradition, such as those in Eastern Europe and Brazil, have typically produced judo fighters who win once judo fighters end up on the ground. That's when competitors struggle to either pin their opponents for 20 seconds or force them to tap out by applying a stranglehold or an armbar, a move where the limb is hyperextended to the point it might break.

RETURNING STAR

Frenchman Teddy Riner is simply the most successful judoka of all time. The 27-year-old heavyweight has won a record eight world championship titles, five European titles and two Olympic medals, including a gold at the London games. At 6-foot-8 inches, Riner strikes an imposing figure on the judo mat but moves surprisingly fast for a heavyweight. Riner tends to dominate by throwing his big right arm over his opponent's head to take control of the fight, and very few of his competitors have been able to prevent Riner from securing a dominant grip on their uniforms.

BEST RIVALRY

After becoming the first American to win a judo gold medal, Kayla Harrison will be looking to defend her title in Rio. Her biggest roadblock might be longtime rival Brazilian Mayra Aguiar, who defeated Harrison at a Paris competition earlier this year with a match-ending throw. The two have now fought 16 times — and split the victories evenly. At a world cup final in Sao Paolo several years ago where Harrison won over Aguiar on penalties, she was booed by the local crowd. Harrison described Brazilian judo fans as "wild" after the experience. "Good thing I don't speak Portuguese, because if I did, I might cry."

OLYMPIAN EFFORT

Two judoka athletes from the Democratic Republic of the Congo will be fighting as part of the IOC refugee team in Rio. Yolande Bukasa Mabika will be competing in the women's 70-kilogram division and Popole Misenga will be fighting in the men's 90-kilogram division. The two are currently training in Brazil. Misenga sought asylum in Brazil when he arrived to compete in the world championships being held there and credits the technical training he has received with making him a better fighter.

"You can't let people think that just because they are refugees, they have to stop what they're doing," he said. "Even though they are refugees, they need to continue practicing their sport."

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Rachel Cohen in New York contributed to this report.