Xu Jiayu set a new Championship Record in the semi-finals of the men’s 100 back in a time of 52.17, lowering Aaron Peirsol’s 2009 mark of 52.19.
25-year-old Sarah Kohler broke her German Record in the preliminary heats of the women’s 1500, qualifying third for the final.
Fanny Lecluyse broke her own Belgian National Record in the women’s 100 breaststroke, qualifying ninth out of the prelims in 1:07.27.
Guilherme Guido set a new South American Record in the men’s 100 backstroke, clocking a time of 52.95 to lower his old mark of 53.09.
Katinka Hosszu has dropped the 100 backstroke at the World Championships after she didn’t show for her preliminary heat on day two.
Adam Peaty became the first man to break 57 seconds in the 100 breaststroke with a world record 56.88 in the semi-finals in Gwangju.
The South African women set a new Continental Record in the 400 freestyle relay on the opening day of the 2019 World Championships.
A pair of 52-second splits in the women’s 400 free relay signal a return to top form for Penny Oleksiak, who helped Canada win bronze on day 1 in Gwangju.
The Australian women lowered their Championship Record en route to winning the 400 free relay in 3:30.21, led by a 51.45 anchor from Cate Campbell.
Alessandro Miressi anchored in 47.57 as the Italian men broke an 11-year-old National Record in the 400 free relay, placing fourth overall.
17-year-old Ajna Kesely set a new Hungarian National Record in the women’s 400 freestyle final in Gwangju, placing fourth in a time of 4:01.31.
Gabriele Detti broke his Italian National Record in the men’s 400 freestyle, winning bronze on the first night at the World Championships in Gwangju.
Darragh Greene broke his own Irish National Record in the prelims of the men’s 100 breaststroke, clocking 59.82 to narrowly miss the semi-finals in 17th.
Elena Di Liddo set a new Italian National Record in the preliminaries of the women’s 100 fly, producing a time of 57.18.
Barbora Seemanova lowered her Czech National Record in the women’s 400 free for the third time in less than a month, touching in 4:09.73.