American Ryan Lochte captured the men's 200-meter individual medley for his first gold of the 2013 World Swimming Championships, while Missy Franklin won her fourth gold as part of the U.S. women's 4x200-meter freestyle team.
Lochte, coming off a disappointing fourth-place finish in Tuesday's 200-meter freestyle, was second halfway through Thursday's race, but put on a finishing kick to claim the title in a time of 1 minute, 54.98 seconds. He was the silver medalist at this event, behind only Michael Phelps, at last summer's Olympics.
Japan's Kosuke Hagino was second, 1.31 seconds behind, while Brazil's Thiago Pereira slipped to third after leading midway through.
Franklin swam the anchor leg to rally the U.S. women to the gold in the freestyle relay. She had already won individual gold in the 200-meter freestyle and the 100-meter backstroke, while also adding team gold in the 4x100-meter freestyle.
Katie Ledecky, who set a world record in the 1,500-meter freestyle earlier this week, got the American team off to a fast start, but Shannon Vreeland fell behind and Karlee Bispo hit the wall to send Franklin into the water trailing the Australian team.
Franklin, though, swam the fastest leg -- by nearly two seconds -- to push past Aussie rival Alicia Coutts. Franklin's split of 1 minute, 54.27 seconds enabled the U.S. to finish first with a combined time of 7:45.14.
Australia was 1.94 seconds behind with France 3.29 seconds off the pace.
James Magnussen gave Australia gold in the men's 100-meter freestyle, edging Americans James Feigen and Nathan Adrian for the title in the premier event of the meet.
Magnussen, known as "The Missile," finished in a time of 47.71 seconds, beating Feigen by .11 seconds and Adrian by .13 seconds. Adrian had edged Magnussen by 1/100th of a second for Olympic gold last summer in London.
Also Thursday, China's Liu Zige won gold in the women's 200-meter butterfly and countrymate Zhao Jing claimed the women's 50-meter backstroke crown.