Hong Kong's Daniel Lee Chi-wo suffered mixed fortunes at the world championships in Lausanne, Switzerland, last week.
Lee, 29, placed a creditable second in the Aquathon Championship in the middle of the week, missing the gold medal by just four seconds.
He then went into yesterday's Olympic distance triathlon full of confidence and hoping to score valuable world-ranking points, but placed a disappointing 64th after clocking two hours, two minutes and nine seconds.
Britain's Tim Don took the gold medal in 1:52:32, finishing 17 seconds ahead of New Zealand's Hamish Carter (1:51:49). Fredric Belaubre, who led the pack out of the swim-bike transition, took the bronze medal in 1:52:12.
The South Africa-based Don, 28, ran a blistering 30:49 for the 10km run.
A group of four athletes came out of the 1,500m swim into the first transition in just over 18 minutes, led by America's Andy Potts. Lee, 29, reached the first transition point some 50 seconds down on the leaders after coming out of the water in 48th position from the 85 starters.
'Daniel had a good swim but dropped off the back of the second pack on the bike section and ended up four minutes down with the third pack going into the run,' said national triathlon coach Ruth Hunt. 'It was a very hilly course and once Daniel knew that he was out of the top 50 and a points-scoring position, there was no point in pushing for a higher place.'
Hong Kong's Ricco Chan Yee-ko clocked 1:03:10 to finish 56th in the men's junior race.