Record-breaking Hong Kong and Australia swimmer Kenneth To has died suddenly aged 26 after falling unwell at a Florida training camp, leaving fellow competitors in shock.
Chinese star Sun Yang, a one-time team-mate of To's, was among the mourners for the popular swimmer who won Commonwealth and world championships medals with Australia before switching to represent his native Hong Kong.
The Hong Kong Sports Institute said To, who held 16 Hong Kong swimming records, was on a three-month training programme at the University of Florida when he was taken ill.
"He felt unwell at a training session and was taken to hospital where sadly, he passed away," a statement said Tuesday, adding that the Institute was "deeply shocked and saddened".
"He was extremely popular and loved by his teammates and competitors. Kenneth was known as a truly exceptional person, warm, funny and kind. His sudden passing is a huge loss to local sports."
Multiple Olympic champion Sun, who teamed up with To for the 4x100m freestyle relay at the 2017 China National Games, was among those to pay tribute.
"Your love and passion for swimming will always be in our hearts, thank you for everything you've given to swimming," Sun posted on Chinese social media.
"May there be no pain in heaven...RIP."
To was part of the Australian teams that won Commonwealth gold in the 4x100m freestyle relay in 2014, and silver in the 4x100m medley relay at the 2013 world championships.
He shifted to represent Hong Kong in 2016, but remains the Australian short-course record-holder in the 100m and 200m individual medley.
"I still can't accept the news of his death, it's so shocking," Hong Kong swimmer Yvette Kong told the Apple Daily newspaper.
"He made a lot of contributions to the Hong Kong swimming world. It is such a pity."