Jakarta, Indonesia: Japan's Rikako Ikee confessed to being "shattered" as she limbered up for her bid to scoop a fourth swimming gold medal at the Asian Games on Tuesday.
Chinese superstar Sun Yang eased to the quickest time in the men's 400 metres freestyle heats, leaving the towering three-time Olympic gold medallist on course for a third title in Jakarta.
Pan Pacific champ Ikee qualified second fastest for the evening's 100m butterfly final as she clocked 57.68 seconds, 13 hundredths behind China's Zhang Yufei.
"I've never been this tired before," said the Ikee, who has already captured gold in the 50m fly, 100m free and the 4x100m free.
"I can't put my finger on why but my body just wouldn't work today," added the 18-year-old, who lit up the recent Pan Pacific championships and has emerged as Japan's brightest medal hope for the 2020 Tokyo Olympics.
"I just felt so heavy. But I'll turn it around in the final and hopefully set a Games record."
Sun, the reigning world champion, topped the timesheets in 400m qualifying, winning his heat in 3:49.13 -- a second and half quicker than Japan's Kosuke Hagino.
Acknowledging the cheers from a noisy section of flag-waving Chinese cheergirls, Sun strode away from the pool deck without talking to media.
Japanese pair Yasuhiro Koseki and Ippei Watanabe won their heats in the men's 200m breaststroke as defending champion Dmitriy Balandin watched on from the stands after pulling out with a suspected foot problem.
"I was a bit surprised not to see him on the blocks but I just need to worry about my own race," said Watanabe, who set the current world record for the event early last year.
"If I can stay calm I'm confident in myself to get the job done."
Yui Ohashi posted the fastest time in qualifying for the women's 400m individual medley as Japan looks to claim top spot in the gold medal table on day three of the six-day swimming competition.