Para-triathlete Markus Häusling has died after losing his battle with amyotrophic lateral sclerosis (ALS).
The 46-year-old German competed at International Triathlon Union (ITU) events all over the world and was ranked inside the world's top 30.
He had hoped to compete at the Rio 2016 Paralympic Games in September until his illness took hold.
Among other achievements, Häusling is a former German champion.
Eric Angstadt Torres, the ITU's manager for Para-triathlon and multisport, led the tributes to a man who was well liked on the triathlon circuit.
"All I can say was that he was one of the athletes that was always holding a nice smile and enjoying every race no matter his result," said Torres.
"He actually appreciated each and every moment in life in a way that so few people do.
"It was his attitude that was so positive and that positive energy is what really made it special to be around him.
"That outlook on life was hit hard in 2015 when, after Chicago he felt it unlikely he would make Rio, but what really disrupted his plans in life was the moment they told him he had ALS.
"We are so lucky to have enjoyed his company as an athlete and as a person.
"He will surely be missed."