Former world silver medallist and Commonwealth Games champion Kenneth To has died suddenly at the age of 26.
To passed away in hospital after complaining of feeling unwell during a training session at the University of Florida.
To won world silver in 2013 as part of Australia's 4x100m medley relay squad, and gold at the 2014 Glasgow Commonwealth Games in the 4x100m freestyle relay.
The Hong Kong-born swimmer reverted to competing for the country of his birth in 2016.
In a statement, the Hong Kong Sports Institute said it was "shocked and saddened" to hear of Ko's death, calling him "a truly exceptional person - warm, funny and kind."