Doha - Chad le Clos set a new world record in the100m butterfly with Katinka Hosszu laying down a new marker in the 100m backstroke at the World Short-Course Swimming Championships.
With world records also set by the Russian men's 4x50m medley relay which was subsequently lowered tonight by Brazil, it brings to seven the number of new global marks after two days at the Hamad Aquatic Centre.
Other winners on Thursday were Mireia Belmonte, the Spaniard who upstaged Hosszu with two gold medals and two world records on Wednesday, in the 800m freestyle while Daiya Seto headed a Japanese one-two with Kosuke Hagino in the 400m individual medley.
Brazilian Felipe Franca Silva claimed the 100m breaststroke, Australia's Mitch Larkin won the 100m backstroke, Ruta Meilutyte took the 50m breaststroke crown and Brazil won the mixed 4x50m medley relay.
Le Clos sat on the lane ropes and celebrated after reducing the 100m butterfly mark by 0.04sec to 48.44 as he claimed his second title of the meet following his 200m freestyle victory.
The 22-year-old had
already threatened the world record this season, just 0.08sec off Evgeny
Korotyshkin's mark at the World Cup in Hong Kong in September.
"I think it was important to get the world record. Usually I race to win but tonight I felt I had to break it," said Le Clos.
"I think a lot of people would have questioned me if I hadn't broken it tonight so I am pretty happy with that."
Le Clos' performance was all the more impressive given Korotyshkin set the previous mark in the performance-enhancing suit era in November 2009.
"I remember watching Evgeny's 48.48 in 2009 in Berlin. I was a 17-year-old boy who didn't make the final. I was watching him and five years later - it's incredible."
Meanwhile, Hosszu dug into every reserve to take the 100m backstroke title and set a new record of 55.03sec, slicing 0.20 off Shiho Sakai's record from 2009.
Australian Emily Seebohm and Daryna Sevina of Ukraine were second and third respectively.
"This is my sixth world record of the short-course season but it ranks pretty high up there because it is an event that is not really supposed to be my event because I am an 'IMer' (an individual medley swimmer) and nobody thinks of me as a backstroker," said Hungarian star Hosszu.
The 25-year-old believes that in time world records will be harder to come by in the 25m pool as they are in the 50m Olympic swimming as long as it becomes more of a focus for the swimmers.
"In short course there are fewer (people) than in long course and Olympics is in a long course pool," explained Hosszu.
"It is still developing -- the short course will get to a level like long course."
Seto led a Japanese one-two with Hagino in the 400m individual medley in an Asian record of 3:56.33.
He led from the blocks and it was just a battle between him and the clock, the Japanese 1.21sec inside Ryan Lochte's world record with 100m to go.
However, he could not sustain such pace -- underlining the pedigree of Lochte's 2010 mark -- and touched 4.84sec ahead of Hagino with Hungarian David Verraszto third in 4:01.82.
Brazil took more than two seconds off the fledgling world record set by Russia in the morning en route to gold in the men's 4x50m medley relay.
Russia had clocked 1:32.78 in an event which governing body FINA have only just started to recognise for record status.
However, it was the Brazilian quartet who set the new standard in the evening finals brought home by former Olympic 50m freestyle champion Cesar Cielo in 1:30.51.
Felipe Franca Silva won the 100m breaststroke in a championship record of 56.29 and then returned to swim the breaststroke leg as Brazil won the mixed 4x50m relay in 1:37.26.
Belmonte took her third gold in the 800m freestyle in a championship record 8:03.41 while Ruta Meilutyte took the 50m breaststroke in 28.84.
Tyler Clary brought the United States home in the 4x200m relay in 6:51.68.