[gallery size="medium" td_select_gallery_slide="slide" td_gallery_title_input="Three world records tumble on first day in pool" ids="74902,74901,74900,74899"] RIO DE JANEIRO —Hungary's Katinka Hosszu ended her long wait for Olympic victory and Australia captured two gold medals in an exhilarating first day of swimming competition that saw three world records smashed Saturday. Hosszu, five times a world champion but without a medal from three previous Olympics, shattered the world record by 2.07 seconds in the final of the women's 400 meters individual medley. Australia's women retained their Olympic title by winning the 4x100m freestyle relay in world record time, with sisters Bronte and Cate Campbell swimming the last two stages to overhaul the United States, despite the efforts of Katie Ledecky on the anchor leg. Mack Horton's victory in the men's 400 freestyle also meant Australia had already doubled their gold medal tally from a disappointing showing four years ago. The results pushed Australia to the top of the medals table and confirmed their return to prominence in swimming, after their poor outing at London 2012. The day's record spree began with Britain's Adam Peaty, who broke his own world mark of 57.92 in the heats of the 100 breaststroke when he clocked 57.55. Tipped to become the first British man to win an Olympic gold since 1988, he then swam 57.62 in the semifinals. In the first of four evening finals, Japan's Kosuke Hagino won the men's 400m individual medley, the grueling discipline that combines butterfly, backstroke, breaststroke and freestyle. Hagino, the bronze medalist in 2012, won with a time of four minutes, 6.05 seconds to end a US stranglehold on the event dating back to 1996. Chase Kalisz of the US, who had been fastest in the heats, finished second and Japan's Daiya Seto took the bronze. In the men's 400 freestyle, Australia's Horton edged out defending champion Sun Yang of China and Italy's Gabriele Detti, pulling ahead in the final quarter after shadowing Britain's James Guy and Conor Dwyer of the US for much of the race. Hosszu then grabbed the spotlight with a stunning victory in the 400 individual medley. Hosszu was already celebrating when American Maya DiRado finished second in 4:31.15, with Spain's Mireia Belmonte claiming bronze in 4:32.39. Having suffered a nightmare Olympics in London, where she started as a hot medal prospect but came away empty-handed, she led from start to finish and stormed down the final length with the crowd roaring her on to the record. In the women's relay, the Australians led off with Emma McKeon while Brittany Elmslie swam the second leg before Bronte Campbell overhauled the Americans and handed over to sister Cate, who touched in three minutes, 30.65 seconds, beating the previous world record of 3:30.98 they set in Glasgow in 2014. Yusra Mardini, the Syrian refugee who was swimming for her life to a Greek island less than a year ago, won her 100m butterfly heat but failed to reach the semifinals. "Everything was amazing. It was the only thing I ever wanted was to compete in the Olympics," said the 18-year-old, who is representing the Games' first ever refugee team. Elsewhere, Thailand's Sopita Tanasan won the first weightlifting gold, the women's -48kg, with a total lift of 200kg. Tanasan, 21, won by 8kg from Indonesia's Sri Wahyuni Agustiani. In third place was Japan's Hiromi Miyake, the 2012 silver medalist who was competing in her fourth Games. Hungary took its third women's gold in Olympic fencing since 2000 as Emese Szasz bounced back from a first-match loss in London to beat Italy's twice world champion Rossella Fiamingo. France came close to ending a long medal drought in Olympic fencing, but a breakout performance by 43rd-ranked Lauren Rembi came up short in the bronze medal bout. Sun Yiwen's third-place finish helped Chinese fans forget the shocking 15-8 loss by her teammate Xu Anqi, ranked first in the world, to Frenchwoman Marie-Florence Candassamy in her first bout. Vietnamese rejoiced Sunday after their country won its first ever Olympic gold medal. Hoang Xuan Vinh, a 41-year-old a serving army colonel who first learned to shoot with AK47 rifles, made history when a near-perfect final shot in the men's 10-meter air pistol clinched him gold. Vinh's victory shunted Brazil's Felipe Almeida Wu and China's Pang Wei into second and third respectively, something that was seized on by jubilant Vietnamese. Serbian rowers Milos Vasic and Nenad Bedik capsized in choppy waters at the Rodrigo de Freitas lagoon, but won a reprieve when they were allowed to move into the next round. The American men's basketball team romped past China 119-62 Saturday night behind Durant's 25 points. Australia opened the Olympic competition earlier in the day with an 87-66 win over France, while Serbia topped Venezuela in the other Group A match. Australia held off Brazil 84-66, Japan downed Belarus 77-73, France defeated Turkey 55-39 and Canada routed China 90
