Ellen Walshe set four Irish national records and finished fifth in a final on the first day of the World Aquatics Swimming Championships (25m) in Budapest.
This morning, the Olympic finalist from Dublin took over a second and a half off her own 200m individual medley national record as she qualified sixth for the final in a time of 2:06.50.
In the final, she was seventh after the backstroke and butterfly legs but moved up to sixth during the breaststroke, and also had a strong freestyle leg to finish fifth in 2:05.52, 2.40 faster than she had started the day.
The two-time Olympian believes the performance was a step-up, taking three-seconds off her time from last year.
"It's a massive step forward from last year and I’m delighted," said Walshe afterwards. "It's another second off this morning’s swim, which I wasn’t sure if we could find, but it was there, so absolutely delighted."
American Kate Douglass won gold in a new world-record time of 2:01.63, just over a second ahead of compatriot Alex Walsh, with Team GB's Abbie Wood claiming bronze (2:02.75)
Walshe also broke her own senior 50m butterfly record twice in making it as far as the semi-finals.
On Tuesday morning, she lowered it from 25.90 to 25.65 seconds and advanced to the semi-finals in 14th place, finishing in the same position despite an even faster swim of 25.45 seconds, which Walshe says was a confidence boost.
"I kind of just used it as a warm-up swim as well and I knew I obviously wanted to be down under 26 (seconds) again tonight," she added.
"I said if that's three records, then let’s make it four. I went into the 200 (IM) a lot more confident than I thought I would this week, because I think of the 50 (butterfly) out in front."
American Gretchen Walsh was the fastest qualifier for the final (top eight) in another new world record time of 23.94.
In the first final of the evening, Canada's Summer Mackintosh also broke the world record by 1.05 seconds in winning gold in the women's 400 metres freestyle in 3:50.25.
It was a disappointing day for Olympian Danielle Hill, who failed to progress from the heats of her main event, the women's 100m backstroke; her third-fastest time of 57.95 seconds (sixth in her heat) was only enough for 19th overall.
Hill was a silver medallist at the European short-course championships in June in a time over two seconds slower. The Larne swimmer returns to action on Wednesday in the 100m freestyle.
Galway's John Shortt lowered his own recent junior Irish record to 51.21 seconds but also fell outside a top-16 place in the men's 100m backstroke while Max McCusker (23.09) was 32nd in qualifying in the men's 50m butterfly.
National Centre Limerick 17-year-old Shortt returns on Sunday for his favoured event, the 200m backstroke, while McCusker will be back in action on Friday in the 100m butterfly heats.
Nathan Wiffen finished ninth in the 1500m freestyle in what was his debut appearance at a World Championships.
The twin brother of 800m Olympic champion Daniel was fourth in the 'fastest heat' - combined with two earlier heats rather than requiring a final - at the 500m mark. He had slipped to sixth by 1000m and finished in that position, coming in ninth overall in 14:32.65.
The gold was won by 19-year-old Tunisian Ahmed Jaoudi (14:60.40), who beat the time set by German Florian Wellbrock in an earlier heat by just .87 of a second. Turkey's Kuzey Tuncelli took bronze.
