British triathletes Jessica Learmonth and Georgia Taylor-Brown were disqualified for crossing the line together in a heat-affected test event for next year's Tokyo Olympics on Thursday.
Learmonth and Taylor-Brown held hands as they crossed the line. Organisers had earlier halved the distance of the running section to 5 kilometres due to concerns over the extreme heat.
Bermuda's Flora Duffy, who finished third behind the pair, was elevated to first in the race that also doubled as an Olympic qualifier.
International Triathlon Union (ITU) officials deemed the British pair were in breach of rules that state athletes must not "finish in a contrived tie situation where no effort to separate the finish times has been made."
Duffy was officially awarded the win with a time of 1:40:19. Italy's Alice Betto was second and Britain's Vicky Holland completed the podium.
"The whole point of coming here was to check out the venue, check out the course and see the conditions," said Duffy, who missed most of last year due to injury.
"I love racing in hot and humid weather and that felt pretty good today."
The ITU decided to reduce the distance of the run section with concerns that the weather conditions at the end of the race would fall within "extreme levels."
The swimming and cycling segments remained the same after the ITU deemed the water quality and temperature in the Odaiba Marine Park course were within regulation.
ITU regulations state that the swimming segment must be shortened or cancelled if the water temperature is above 30.9 degrees Celsius, but the highest water temperature measured Thursday was 30.3.
On Wednesday, the ITU had moved Saturday's Paratriathlon World Cup start time forward by one hour to avoid exposing athletes to high temperatures.
The World Cup, a test event for next year's Paralympics, will begin at 6:30 a.m., with all athletes expected to finish the race by 9:30 a.m. Thursday's triathlon began at 7:30 a.m. local time.
With less than a year to go until the start of the Olympics, athletes' ability -- or lack thereof -- to cope with the extreme heat has been a key concern for organisers and sports bodies.
Soaring temperatures have killed at least 57 people across Japan since late July, highlighting the possible health threat to athletes and fans.
Kyodo News reported last weekend that several athletes were treated for heatstroke at the 2019 World Rowing Junior Championships in Tokyo, which was another test event for Olympic organisers.