Rapsys’ 1:40.95 broke Park Tae Hwan’s Championship Record of 1:41.03.
Boglarka Kapas didn’t show for the women’s 400 free prelims.
Dressel opted out of the men’s 50 fly on day 4.
Pawel Juraszek clocked 20.98 to win the 50 free swim-off over Jesse Puts.
Jack Conger will swim on the both the 4×50 and 4×200 free relays for the U.S. at day 4 prelims.
World record holder Alia Atkinson will be seeking a three-peat in the women’s 100 breast.
Olivia Smoliga led off the mixed medley relay under her official American Record in the 50 back.
Mallory Comerford moved into a tie for 9th all-time in the 100 freestyle with a new American Record of 51.63.
Ryan Murphy tied the official American Record in the men’s 50 back semi-finals.
Femke Heemskerk had a blazing 22.90 anchor for the Netherlands as they broke the European Record and went under the old world record.
Olivia Smoliga and Kelsi Dahlia both played a crucial role in helping the Americans break the world record in the 4×50 mixed medley relay.
Caeleb Dressel broke the American Record again to qualify 1st for the final in 20.51.
Kirill Prigoda broke the world record by nearly three-tenths in the men’s 200 breast.
Evgeny Rylov broke an eight-year-old National Record in the men’s 50 back semis.
Li Zhuhao lowered his Asian Record once again as he won bronze in the men’s 100 fly final.