Riki Nakaya and Nae Udaka both struck gold respectively in the men's 73-kg and women's 57-kg divisions at the world championships on Wednesday.

Nakaya, a silver medalist at the London Olympics, defeated Hong Kuk-hyon of North Korea by ippon to win his second career world title, and his first since 2011. The division's defending champion Shohei Ono was eliminated in the round of 16 by South Korea's Lee Young-jun.

"It's great to be back on top of the world," Nakaya said. "With Ono losing, I thought I had no excuse for not winning the 73 kg. This title is huge."

Udaka won her first championship in extra time over Portugal's Telma Monteiro. Kaori Matsumoto, who took gold at London in the weight class, lost to American Marti Malloy by ippon in the second round.

"I have a lot to go over regarding my performance," Udaka said. "But I fought on spirit alone today. I finally feel like I'm one of the top judoka now."