Sixteen-year-old Rio Olympian Rikako Ikee won the women's 50-meter butterfly and 50m freestyle on Friday at the Asian swimming championships.

Ikee held on to her lead in the butterfly and touched the wall in 25.74 seconds, while she came from behind in the following race to win the freestyle by a hundredth of a second in 24.90 at Tokyo Tatsumi International Swimming Center.

"I was worried about the fatigue given the short interval between the races, but I didn't give in and that paid off," Ikee said. "I could show the passion I have for the 50 freestyle."

Reona Aoki, 21, won the 200 breaststroke after clocking 2 minutes, 22.74 seconds, while 19-year-old Ippei Watanabe won the men's 100 breaststroke in 59.99.

In synchronized swimming, Yukiko Inui and Mai Nakamura claimed the duet technical routine title with 90.3333 points, holding off China, which chose to not to field its best pair and scored 88.5092.

"I learned this (routine) within a month so I was pushed to my limit but I'm relieved," said Nakamura, who replaced Risako Mitsui, who retired after winning the duet bronze medal with Inui at the Rio Games.

"There's nothing negative in changing the partner. Hopefully we can come up with a new routine," Inui said.

Japan defeated Iran 15-6 in the semifinals of the men's water polo, securing a berth in the world championships next July in Budapest.