She is competing in the Women's Laser Radial
Annalise Murphy has won her first race at Rio 2016, leading the way in the Women's Laser Radial Opening Series.
Murphy came very closet to medalling four years ago at London 2012, just missing out with a fourth place finish in the medal race.
In today's action, she was seventh after the first mark before quickly climbing the order and reaching first place after four marks.
Her time of 50:57 was 21 seconds clear of Belgium's Evi van Acker and 29 clear of China's Lijia Xu.
She will now hope to follow up that excellent start with another victory in Race 2 as she tries to build towards the medal race.
This is a marathon, not a sprint for @Annalise_Murphy - that was just the first of 10 normal races, with the medal race next Monday— Off The Ball (@offtheball) August 8, 2016
Meanwhile, fellow Irish contender Finn Lynch was outside the Top 10 in the men's event:
Lynch finished in a time of 53:29.