Britain's James Goddard broke the British and Commonwealth record as he and Gregor Tait both qualified for the final of the men's 200m backstroke.
Goddard is hoping for a medal
Goddard comfortably won the first semi-final in 1:57.25, beating Tait's old mark of 1:57.42.
Tait proceeded to finish third in the second semi behind 100m champion American Aaron Peirsol, who just missed his own world record in 1:55.14.
Austrian Markus Rogan finished second ahead of Tait.
Goddard had earlier won his morning heat ahead of Tait as they qualified second and fifth fastest respectively.
"This morning I went off hard and backed off in the last 25m, but tonight I thought I may as well go for it a bit more," Goddard said.
"Hopefully I can go a bit faster in the final because I am looking for a medal to be honest."
Tait also feels he has room for improvement in Thursday's final.
"It is getting better each time so hopefully it will come right tomorrow," he said.
"Stephen Parry gave us a massive lift and we all want to do the same as him now."