ISTANBUL, Turkey -- Daiya Seto of Japan won the 400-metre individual medley on Thursday at the short-course world championships while Noemie Thomas set a Canadian record in the women's 50-metre butterfly semifinal.
Seto had the best time in the heats and then finished in three minutes 59.15 seconds to win gold. Laszlo Cseh of Hungary won silver in 4:00.50 and compatriot David Verraszto took the bronze in 4:02.87.
The Japanese swimmer started built a lead in the breaststroke leg, his strongest discipline, and held on the rest of the way. World record-holder Ryan Lochte of the United States did not race in the event.
Thomas, a 16-year-old swimmer from Richmond, B.C., finished her race in 25.76 seconds. Her fourth-place result qualified her for Friday's final.
"I knew I had it in me," she said. "It was more a matter of keeping calm -- this is the biggest meet I've ever been to in my life -- so it was just a matter of keeping calm and just knowing, having the confidence that I had done the work and done the training."
Katerine Savard set the previous national record of 26.49 seconds at last year's Canada Cup in Montreal. Jeanette Ottesen Gray of Denmark won Thursday's semifinal in 25.62 seconds.
Canadian short-course team coach Tom Johnson said this event serves as an opportunity to pick up valuable experience against top-flight competition.
"It's about taking a step and putting these kids into the international arena as often as we can to try to develop the competitive heartiness and skills that they need to compete at the highest level," he said.
In the women's 100-metre freestyle semifinal, 18-year-old Chantal van Landeghem of Winnipeg didn't advance after finishing 14th in 54.16 seconds. The top eight swimmers moved on to the final.
Ruta Meilutyte set a championship record of 29.44 seconds to win gold in the women's 50 breaststroke.
"I really didn't expect it," said the 15-year-old Lithuanian, who won the 100 breaststroke at the London Olympics. "At the moment, it feels just like I have swum a normal race, but it will start sinking in. It's crazy."
Alia Atkinson of Jamaica took silver in 29.67 and Australia's Sarah Katsoulis earned bronze in 29.94. World record-holder Jessica Hardy of the United States was fifth.
American Matt Grevers won the 100 backstroke in 49.89 seconds, barely defeating Stanislav Donets of Russia (49.91) in the next lane. The American won Olympic gold in the event.
Guilherme Guido of Brazil won bronze in 50.50.