Backstroke specialist Xu Jiayu broke the Asian record of the men's 100m backstroke at the Chinese Swimming Championships here on Wednesday.
Xu, 21, took the gold of the event in 51.86 seconds, and sliced a big margin from the previous Asian record of 52.24 seconds.
"I thought I might break the national record tonight, but I never thought I could swim into 52 seconds," said Xu who took the silver medal of the event at the 2016 Rio Olympic Games in a national record breaking pace of 52.31 seconds.
Xu trailed behind Ryan Murphy in Rio and his new Asian record is only 0.01 shy of the world record, set up by the American in the medley relay at the 2016 Olympic Games.
"Maybe I could break the world record if I improve a tiny detail. It's unpredictable," said Xu, who attributed his record performance to his confidence. "But I won't think about breaking the record, neither the World Championships nor the National Games. I don't want to put too much pressure upon myself."
Fu Yuanhui, Xu's teammate in both the national and provincial squads, also improved her personal best in the women's 100m backstroke as she set a national record of 58.72 seconds, 0.04 seconds faster than her Olympic bronze medal winning time in Rio last year.
Fu, 21, went all out in the final and got cramp after leaving the pool. "I was surprised by the result. I didn't perform well in the last two days. Then I realized that I should be more anxious for the race," said Fu.
"If I'm not nervous, I could not swim fast," said Fu. "I could hardly sleep while I was trying to adjust my state. And this morning, I felt I was nervous and I even wanted to vomit after having breakfast."
The two records stole the spotlight of Sun Yang partly although the Olympic champion dominated the 200m freestyle in one minute and 44.91 seconds.
Sun's result was 0.26 seconds slower than his winning mark at the Rio Games but was still faster enough for him to clinch the Olympic title as the second-placed Chad Le Clos from South Africa finished the race in one minute and 45.20 seconds.
In the morning session, Sun took the top place of the 800m freestyle heats in eight minutes and 0.66 seconds.
Yan Zibei led the men's 50m breaststroke heats in 27.36 seconds, slicing the previous national record by 0.02 seconds.
The 21-year-old Yan broke the national record of the 100m breaststroke on Monday.
In the other two finals on Wednesday, Hou Yajie claimed the gold of the women's 1,500m freestyle in 16 minutes and 13.37 seconds. Shi Linjing finished first in the women's 100m breaststroke in one minute and 6.94 seconds.