Hungaria's "Iron Lady", 27-year-old Katinka Hosszu, smashed the 400m Individual Medly World Record to win gold at the event in Rio de Janeiro on the first day of games at the 2016 Olympics.

This was the second world record broken on the first day of swimming.

She finished the race at a time of 4:26.36 minutes. USA's Madeline Dirado finished second five seconds later at 4:31.15 and Spain's Mireia Belmonte won Bronze.

Meanwhile Australians set a world record to claim gold over the U.S. in the 4x100m freestyle relay with a time of three minutes, 30.65 seconds. Emma McKeon, Brittany Elmslie, Bronte Campbell and 100m freestyle world record holder Cate Campbell topped the American quartet of Simone Manuel, Abbey Weitzeil, Dana Vollmer and Katie Ledecky, who raced to 3:31.89.

Canada won bronze.