Katie Ledecky held off Sarah Sjostrom in a thrilling 200 metre freestyle final to claim her second gold medal of Rio 2016 on Tuesday.
Already the dominant winner of the 400m freestyle in a world record time, Ledecky was anticipated to face a stiffer challenge over the shorter distance.
Sjostrom, who won the 100m butterfly final on Sunday, had qualified fastest for the final and came on strong over the final 50 metres.
Yet Ledecky had too much for the Swede as she triumphed with a time of one minute and 53.73 seconds to strike gold once again.
The 19-year-old American appears certain to claim another victory in the 800m freestyle later this week, having also earned a silver medal as part of the 4x100m relay team.
Australia's Emma McKeon (1:54.92) claimed bronze on Tuesday behind Ledecky and Sjostrom (1:54.08)