TOKYO -- China's Wang Jianjiahe on Monday set a new Asian record in qualifying second for the women's 1500m freestyle final, with the event appearing on the Olympic stage for the first time.

World record holder Katie Ledecky of the United States is the strong favorite to become the first Olympic champion in the event, and qualified first with a new Olympic record of 15 minutes 35.35 seconds.

Wang has emerged as a frontrunner to medal in the event, and will swim in the final as second seed to Ledecky, having made 15:41.59 in the heats.

In the women's 200m freestyle, Rio gold medalist Ledecky finished in 1 minute 55.28 seconds as the top seed for the semifinal. She could now become the first swimmer to win this event at multiple Games.

After competing in the 400m freestyle final and 200m freestyle heats, the 1500m freestyle heat was Ledecky's third race of the day.

"I'll sleep well tonight, I'll tell you that. I was just happy how it went, happy it's over, and I got the job done," said Ledecky.

Yang Junxuan qualified sixth in the women's 200m free semifinal with 1:56.17, meaning she has a chance of becoming the second Chinese swimmer to win an Olympic medal in the event, after Pang Jiaying took bronze in 2008.

"I can't wait to swim a real one after watching teammates competing for days. It was a tough heat, and I thought the result was within my expectations," said Yang.

The semifinalists are also confirmed for the men's 200m butterfly and women's 200m individual medley.

Yu Yiting of China swam a 2:10.22 in the women's 200m IM semifinal. Defending champion Katinka Hosszu of Hungary and Japan's Yui Ohashi also qualified for the 200m IM semifinal. Ohashi won the women's 400m individual medley on July 25, and can become the first Japanese woman to win two gold medals at a single Olympic Games.