Yu Zidi of China prepares to compete in the women's 200-meter medley semifinal at the World Aquatics Championships in Singapore.

Yu Zidi of China prepares to compete in the women's 200-meter individual medley heat at the World Aquatics Championships in Singapore.

Yu Zidi of China prepares to compete in the women's 200-meter individual medley heat at the World Aquatics Championships in Singapore.

Yu Zidi of China warms up to compete in the women's 200-meter individual medley heat at the World Aquatics Championships in Singapore.

Yu Zidi of China competes in the women's 200-meter individual medley heat at the World Aquatics Championships in Singapore.

Mio Narita of Japan, left, and Yu Zidi of China, center, compete in the women's 200-meter individual medley heat at the World Aquatics Championships in Singapore.

Yu Zidi of China competes in the women's 200-meter individual medley heat at the World Aquatics Championships in Singapore.

Yu Zidi of China competes in the women's 200-meter individual medley heat at the World Aquatics Championships in Singapore.

Yu Zidi of China competes in the women's 200-meter medley semifinal at the World Aquatics Championships in Singapore.