Harriet West shattered the Welsh 50m butterfly record at the International Swimming League (ISL) meeting in Budapest.
The Loughborough-based swimmer clocked 26.02 secs competing for London Roar.
West’s time took 0.15secs off the national short-course record of 26.17 set by Alys Thomas in Swansea in 2015.
The 23-year-old, whose previous best was 26.36 secs, finished fifth as Ranomi Kromowidjojo won in 24.74
In the 200m free in Budapest fellow Welsh swimmer Kathryn Greenslade was seventh in 1:59.21 for Aqua Centurions.
The new-style ISL, in its second year but hit by the COVID-19 restrictions, is being held at Duna Arena.
Swimmers are staying on Margaret Island, which is in the middle of the Danube river which runs through the city.
Many of the world’s best swimmers have returned to competition in Hungary for the first time since the coronavirus decimated the calendar.
Matt Richards is competing for the New York Breakers team while Georgia Davies is swimming for Energy Standard.