Katinka Hosszu claimed her second gold medal of Rio 2016 in the women's 100 metre backstroke on Monday.
The Hungarian had already won the 400m individual medley at the Olympic Aquatics Centre on Saturday.
And the 27-year-old triumphed again in the 100m backstroke with a time of 58.45 seconds, 0.30s ahead of American silver medallist Kathleen Baker.
Kylie Masse of Canada and China's Fu Yuanhui took bronze in 58.76.
Australian pair Emily Seebohm and Madison Wilson were a distant seventh and eighth respectively.