The All Japan Judo Federation had announced that current world champions who won the final Grand Slam of 2019 in their home country, would be selected for the Tokyo 2020 Olympic Games, subject to final approval from the country's High Performance Committee.

Fellow world champions Uta Abe and Joshiro Maruyama were beaten in their finals on Friday, costing them the chance to secure spots at the home Games months in advance.

But Sone did not miss the opportunity, getting the better of the Cuban thanks to an o-uchi-gari two minutes into a sudden-death golden score period.

It means the Japanese now leads their head-to-head record 3-1, with an intriguing likely rematch next year in Tokyo.

Sone's main rival for the sole berth at the Games was 2018 world champion Sarah Asahina, who was eliminated in the second round in Osaka by Beatriz Souza. Asahina fought her way through the repêchage rounds before winning her bronze medal contest against compatriot Wakaba Tomita.

Best of the rest

Japan had won eight out of nine golds finals the last day in Osaka, and added three more including Sone's on Sunday.

In the -78kg category, the two-time -78kg world champion and Pan American Games holder Mayra Aguiar was given a big shock in Osaka.

The Brazilian was stunned by world junior champion Rinoko Wada, ending her season on a surprising note.

Aguiar had been hoping to make an impression ahead of her bid for a third Olympic medal – the 28-year-old claimed bronze at London 2012 and on home soil at Rio 2016.

World champion from 2018 Shori Hamada, the favourite for Japanese selection in this weight class, was defeated in the final by compatriot and 2015 world champion Mami Umeki, who propelled herself into the Olympic selection reckoning with a win by ippon.

On the men's side, the three finals on the last day were won by athletes from three different countries.

Beka Gviniashvili of Georgia clinched victory in the -90kg category, beating Uzbekistan's Davlat Bobonov with an ippon in golden score. It was Gviniashvili's first Grand Slam win on the World Judo Tour circuit since 2016. Shoichiro Mukai, this year's Worlds silver medallist, was the top-ranked Japanese, seeing off teammate Kenta Nagasawa in the bronze medal bout.

Olympic bronze medallist Ryunosuke Haga clinched his first Grand Slam title since 2015 by winning the -100kg division, sending out a warning to his Olympic selection rivals. Haga has been through repeated injury setbacks since Rio 2016, but won his first IJF medal in two years by beating Rio silver medallist Elmar Gasimov of Azerbaijan with a waza-ari score. Kentaro Iida and world bronze medallist Aaron Wolf, the top two ranked Japanese judoka in this weight category, both had to settle for bronze.

In the +100kg, Russia's 21-year-old Inal Tasoev shined the brightest in the absence of double Olympic champion Teddy Riner, world champion Lukas Krpalek, and Japan's world and Olympic silver medallist Hisayoshi Harasawa.

Tasoev lived up to his growing reputation to see off local hope Hyoga Ota in the final by waza-ari to make himself the favourite to be named as Russia's Tokyo 2020 representative in the heavyweight division.