Doncaster's Max Litchfield stormed a new British record in the 200m individual medley heats at the World Championships in Budapest.
Litchfield won his heat in the morning session in one minute, 56.64 seconds, breaking his existing British record by more than half a second.
The City of Sheffield swimmer qualified third fastest for Wednesday night's semi-finals behind Japan's Kosuke Hagino and American Chase Kalisz.
Fellow Brit Mark Szaranek also qualified for the semis in 1.59.68.
The 200m IM is Litchfield's second event behind the 400m IM, in which he broke the British record at the national trials in Sheffield earlier this year.
Meanwhile, Great Britain qualified fourth fastest for Wednesday night's 4x100 metres mixed medley relay - giving Adam Peaty the chance to go for two gold medals in an hour in Budapest.
Peaty, the 100m breaststroke World and Olympic champion, is favourite to win over 50m on Wednesday evening after twice lowering his own world record on Tuesday.
And then the 22-year-old Uttoxeter swimmer is expected to come into the mixed medley relay team an hour later for a final which saw Britain qualify behind the United States, Australia and Canada.
The mixed medley relay has been added to the Olympic programme for the Tokyo 2020 Games.
Britain won world gold in Kazan, Russia two years ago in a world record of three minutes 41.71 seconds, with Peaty on the breaststroke leg.
The United States improved that mark in the second of four heats on Wednesday morning to 3mins 40.28secs and Britain went in the fourth heat.
Georgia Davies on backstroke, Ross Murdoch on breaststroke, James Guy on butterfly and Freya Anderson on freestyle clocked 3:44.79 as they finished behind Australia's 3:44.13.
Canada finished second to the USA in the second heat to advance third quickest in 3:44.46.
Duncan Scott was one of four swimmers to clock 48.46 in the 100m freestyle heats, advancing equal fifth fastest behind Cameron McEvoy of Australia, who was the only man to dip beneath 48 seconds, clocking 47.79.
Thomas advanced in 14th place in the 200m butterfly in 2:09.13, behind fastest qualifier Katinka Hosszu of Hungary in 2:07.25. Charlotte Atkinson finished 21st in 2:10.68.
Davies qualified fourth fastest in the 50m backstroke, in 27.73 as China's Fu Yuanhui advanced quickest in 27.21. Kathleen Dawson was 19th in 28.42, missing out on a place in the semi-finals.