The United States relay of Regan Smith, Lilly King, Gretchen Walsh, and Kate Douglass put an exclamation point on an exciting week in Budapest with two world records in one race. Smith broke the 100 backstroke world record, leading off the women's 4×100 medley relay, which was a sign of things to come as the team blew away the relay world record with a 3:40.41.
Smith got the United States off to an electric start. She smashed her world record in the women's 100 backstroke with a 54.02, breaking both her official mark from the Singapore stop on the World Cup circuit and the unofficial world-best she swam leading off the mixed medley relay earlier at this meet, which did not count as an official mark because it came from a mixed relay.
Her 54.02 put the United States well ahead of the world record line for the women's 4×100 medley relay and gave the team a 2.86-second lead on the field. Qian Xinan was the only other woman to break 57 seconds, swimming a 56.88 to give China a slight edge over the rest of the field that was littered with 57-mids from Sara Curtis, Abbie Wood, and Lora Komoroczy.
King extended the United States' lead over the field with a field-best 1:03.02 100 breaststroke split. King claimed silver in the individual 100 breaststroke and, earlier in the session, took bronze in the 50 breaststroke. But she's shown during her long career that she knows how to show up for the relay, and she did so again on day six in Budapest.
100 breaststroke world champion Tang Qianting had the next fastest split in the field, swimming 1:03.17 to keep the Chinese squad in second place. Meanwhile, 21-year-old Angharad Evans swam a 1:03.18 to move Great Britain into third place at the halfway point of the relay.
The Neutral Athletes 'B' jumped from seventh to fourth after a 1:03.26 split from Evgeniia Chikunova. She was the final sub-1:04 split in the field as the Japanese, Italian, Swedish, and Hungarian breaststrokers all turned in 1:04s.
Walsh ended her incredible week with a 52.84 100 butterfly split. Earlier this meet, she became the only woman to break 54 seconds-and then 53 seconds-with a flat start in the 100 butterfly, setting a world record in the prelims, semis, and final of the event. So, it's no surprise that she once again blew away the field on this relay split.
Walsh was 1.83 seconds faster than Louise Hansson, who put together a 54.67 performance for the second-fastest split in the field. The swim was much faster than the 55.23 she swam for fourth in the individual event final. It also helped Sweden move from sixth into fourth place and only .27 seconds behind third-place Great Britain with one leg remaining.
Japan and Great Britain got strong splits from their rising stars. 17-year-old Mizuki Hirai swam a 55.44 for the Japanese relay, pulling them into sixth. Fresh off setting a world junior record in the 50 freestyle final, 18-year-old Eva Okaro split 56.11 for Great Britain.
Douglass stomped to a 50.53 anchor leg, bringing the United States quartet home for a final time of 3:40.41, breaking the world record by 3.94 seconds. Her time gave the United States the fastest split on all four legs of the relay.
Freya Anderson turned in a 51.11 anchor for the Great British squad, running down Liu Shuhan in the closing meters and getting her hand on the wall for silver in 3:47.84, nine-hundredths ahead of the Chinese quartet. Liu kept China on the podium, though, clocking a 51.63 to outlast Sweden's Sara Junevik for bronze. Junevik's 51.35 was the third-fastest split in the field, but she ran out of room to track down Great Britain and China, so Sweden took fourth in 3:48.35, exactly a second ahead of the Neutral Athletes 'B.'