Heat sabotages Aussie triathlon women

Extreme heat has sabotaged the bid of Emma Jackson and four compatriots to claim the first of three spots open to Australia for the Tokyo Olympics triathlon, with organisers forced to cut the run leg of the test event in half.

The fastest of Australia's five-strong women's contingent was initially guaranteed an automatic 2020 nod if they were the first to be on the podium on the Olympic course at Odaiba Marine Park on Thursday.

However, their plans were thrown out the window when organisers cut the 10km run leg in half due to Tokyo's steaming conditions - reported to be over 30 degrees and 85 per cent humidity.

Under Australia's selection policy, athletes can only qualify for the Olympic event if the course is a 1.5km swim, 40km bike and 10km run.

In the end, 2012 London Olympian Jackson was Australia's top finisher at 15th after Bermuda's two-time world champ Flora Duffy claimed victory amid controversy.

"I had a really good swim, probably my best ever, coming out towards the front," Jackson said.

"I still think it was a decent race. It wasn't what I wanted or when I was racing where I thought I would end up, so a bit of disappointment but also positives.

"I'm not exactly happy with the result but I was still top Australian."

Jackson is hoping for a Tokyo berth after overcoming a series of serious injuries - including to her foot, quad and back - after indicating she was back to her best with a maiden World Triathlon Series (WTS) victory last month in Edmonton.

She was Australia's top finisher in a 65-strong field ahead of Ashleigh Gentle (24th), NatalieVan Coevorden (28th), JazHedgeland (36th) and EmmaJeffcoat (44th).

Seven athletes failed to finish in the women's field as they succumbed to the stifling conditions.

There were no official complaints over world body ITU's decision to cut the run leg amid the heat which they made "to put athlete safety first".

However, there was controversy at the finish.

British pair Jessica Learmonth and Georgia Taylor-Brown crossed the line first holding hands but they were later disqualified for trying to tie for the win - an ITU no-no - gifting third-placed Duffy the win after having their appeal dismissed.

Italy's Alice Betto was officially second while Briton Vicky Holland completed the podium.

The men's race takes place on Friday.