Earlier in the day, 18-year-old South Korean swimmer Hwang Sun-woo fell just short of a medal in the men's 200-meter freestyle.
He finished seventh in the final with a time of 1-minute-45.two-six seconds.
It was an agonizing end, Hwang having been in the lead until the 150-meter mark.
The gold went to Britain's Tom Dean.
Hopes were high for Hwang, who was the first South Korean to make the final since Park Tae-hwan in 2012.
But Hwang has a couple more chances left in the 50 and the 100-meter freestyle.
The heats for the 100-meter start tonight at 7 PM.
And the 50-meter heats are on Friday.