Britain's Stephen Clegg set a new world record in the S12 men's 100m butterfly on the last day of the British Para-swimming International Meet.
Clegg, 25, clocked 56.75 seconds at the event in Sheffield, which doubles as trials for the Tokyo Paralympics.
It beat the previous best, set by Russia's Roman Makarov in 2013, by nine hundredths of a second.
"I'm buzzing with that time. No-one can ever really complain with a world record," said Clegg.
Clegg, who is a younger brother of Paralympic athletics gold medallist and Dancing on Ice star Libby Clegg, won silver in the event at the 2019 World Championships.
Coached by Chris Jones, the Edinburgh University Swimmer, who is visually impaired, is now in line to make it to his second Paralympics later this year having made his debut at Rio 2016 where he missed out on a medal.
"I've been doing a lot of work this season around the butterfly and I thought I was in a good place to do something pretty special with it," he added.
"But I think I've got a lot more to give throughout the year. Everything is really clicking on all my events, even the ones I've not really worked on that much.
"It's a great starting point with the first main competition of the season and a great building block for the next five months to come.