Teen Titan comes of age

Her performance has also added another chapter to a strong Chinese tradition in the 200 IM.

Ye won the event at the 2012 London Olympics at 16. Yu Yiting has emerged as another leading Chinese medley swimmer, with her and Yu Zidi pushing each other to constantly improve.

"She is a strong opponent and she pushes me to keep working hard," Yu Zidi said of Yu Yiting.

Yu Yiting added: "We have to keep breaking the Asian record before we can dare to think about the world record. Only then can we have a chance to challenge McIntosh or other outstanding swimmers at the 2028 Olympics."

Veteran Wang Shun, who has competed in five Asian Games, also sees the value of the competition between the two young swimmers.

"They are always chasing each other. If there is only one person, progress will be slower. When there is a rival, you demand more from yourself," Wang said.

From Ye's 2:07.57 set in 2012, over the past year, the Asian record in the women's 200 IM has fallen three times — Yu Zidi's 2:07.41 at last November's National Games, then Yu Yiting's 2:06.82 at the National Swimming Championships in June and, now, Yu Zidi's 2:06.10 in Nagoya.

Yu Zidi's rise has been rapid, but its foundations were laid years ago.

At age six, she first took an interest in swimming after visiting a water park with her father. Coach Li Chao noticed her natural feel for the water: while other children were afraid, Yu Zidi could float by herself and move smoothly through the water.

At nine, she entered a local swimming club in Hengshui, Hebei province and began training with the provincial team after reaching the national first-class athlete standard. Her coaches designed a balanced program across four strokes, with the IM eventually becoming one of her strengths.