Fabio Scozzoli split 25.51 on breast as the Italians broke their National Record in the 4×50 medley relay.
Zhu Menghui clocked 23.95 to tie Rikako Ikee’s Asian Record.
Smoliga has now won six gold medals at the Championships.
Etiene Medeiros got under her 2016 record of 23.88 in 23.82.
Santos clocked 21.81 to break Chad Le Clos’ 2014 Championship Record of 21.95.
Di Liddo’s 56.06 broke Ilaria Bianchi’s 56.13 from 2012.
Melanie Margalis broke the American Record in 2:04.62, winning silver behind Katinka Hosszu.
Caeleb Dressel had the fastest butterfly split in the field at 21.70.
Ryan Murphy will be the lead-off man for the U.S. on the 4×50 medley.
Frenchman Damien Joly broke the France National Record in the men’s 1500 free prelims.
Cameron van der Burgh highlights the men’s 50 breast at day 5 prelims in Hangzhou.
Katinka Hosszu didn’t show for her 100 fly heat shortly after swimming the 200 IM.
Wang Shun didn’t show for his 400 IM heat on day 5.
Andrew Wilson will be the U.S. breaststroker for the 4×50 medley relay prelims.
Freya Anderson won the 200 free in a best time on the opening night of the Ontario Junior International meet in Toronto.