Russia's Egor Mgdsyan and South Korea's An Changrim were surprise winners on the second day of action at the International Judo Federation (IJF) Junior World Championships in Fort Lauderdale.
The duo secured gold medals in the male under 66 and under 73 kilogram divisions respectively.
There were also wins for Frenchwoman Amandine Buchard and Momo Tamaoki, who claimed a fourth Japanese gold of the Championships so far.
Berlin Junior European Cup winner Mgdsyan lined up against reigning Summer Youth Olympic Games champion Hifumi Abe of Japan in the men's under 66kg decider and looked to be struggling early on as Abe took control with a waza-ari from an osoto-otoshi before adding a yuko from an ouchi-gari.
Few expected Mgdsyan to find a route back into the contest but the resolute Russian continued to graft and scored a waza-ari with a pick-up, before adding a second waza-ari from a sasae-tsurikomi-ashi with 47 seconds left in a thrilling final.
Baruch Shmailov of Israel had too much for Ukrainian Bogdan Iadov to secure the first bronze medal on offer, while the second was picked up by Brazil's Ricardo Santos Junior.
Meanwhile, unseeded An powered his way to a surprise win in the men's under 73kg class.
The South Korean won four of six contests by ippon, including the gold medal match against Junior All Japan Championships winner Yuji Yamamoto.
An scored two waza-ari without reply to win by wazari-awasette-ippon, while bronze medals went to Sharofiddin Boltaboev of Uzbekistan and Azerbaijani Huseyn Rahimli respectively.
Two quick-fire waza-aris saw Buchard claim the women's under 52kg title as the senior World Championship bronze medallist lived up to her billing as the gold medal favourite.
The 19-year-old from France overcame Jeju Grand Prix bronze medallist Larisa Florian of Romania.
Astride Gneto joined her compatriot on the podium after defeating Croatian Tena Sikic for bronze as Japan's Mako Uchio overcame Jessica Pereira of Brazil.
After winning three titles yesterday, Japan were not quite as prolific today.
But a fourth title of the Championships was sealed by Junior Asian Championships winner Tamaoki in the women's under 57kg.
Tamaoki was up against compatriot Christa Deguchi and threw her teammate for ippon after just 54 seconds with a thunderous osoto-otoshi to take the victory.
Russia and Canada occupied the third step of the podium after wins for Daria Mezhetskaia over Israel's Timna Nelson Levy and Catherine Beauchemin-Pinard over Dewy Karthaus of The Netherlands.
Day three will see action in the women's under 63kg and under 70kg divisions, while medals will also be handed out in the men's under 81kg and under 90kg categories.
Watch the latest action on Judo TV here.
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