Melissa Bishop-Nriagu can’t overcome injury and can’t get out of the 800-metre heats.

TOKYO—The women’s 800metre race has been all but reinvented, slashed to its estrogen essence.

No Caster Semenya. Indeed, none of the medallists from the Rio Games were to be found in the running lanes for Friday’s heats — barred from participating because of their high testosterone levels.

Intersex athletes as they’re known — a term rejected by nearly all of them — have atypical chromosomes or sex characteristics, sometimes females with internal testes.

Born that way. Which was formerly a competitive blessing and now a curse.

Semenya, the two-time Olympics champion from South Africa, Burundi’s Francine Niyonsaba and Kenyan Margaret Wambui — one-two-three five years ago — deemed not woman enough for the event, each refusing to take drugs that would lower her testosterone quotient, as commanded under revised policy by World Athletics for races between 400 metres and a mile.

The ethical debate continues to rage.

But for the here and now, Canada’s Melissa Bishop-Nriagu, an 800-metre specialist, couldn’t take advantage of the adjusted circumstances. The 32-year-old from Eganville, Ont., the Canadian record holder, with a hamstring bandaged from a recent injury, finished fourth in her heat and failed to advance to the semifinals.

She was heartbroken, after all the time and training put into achieving elite fitness again following the birth of her daughter three years ago.

Bishop-Nriagu ran two minutes and 2.11 seconds, leading for much of the race but fading down the stretch.

Jamaica’s Natoya Goule, looking relaxed on a brutally humid and overcast day, was the fastest qualifier from the six heats in 1:59.83.

In Rio, Bishop-Nriagu had been fourth, agonizingly close to a medal, but part of that 800-metre cadre that usually found itself celebrating apart from Semenya et al, as if running a race within a race. She’s never publicly commented on whether the physiological advantage of the now banned competitors was unfair.

That opening is now gone, at least for her, although she fully intends to contest the 800 at the world championships in Eugene, Ore., next summer.

“I think you have to run these rounds as a final and today that was all I could give you,’’ Bishop-Nriagu said.

At that point,she didn’t know if her time was good enough to proceed to Saturday’s semifinal. She was in the third heat and had to wait, watching three more heats, for her fate to be determined.

“Oh, you know, it’s not a nice position to be in. This is my third Games and I know a lot can go down on that track, no matter the round.’’

But the 2015 world silver medallist admitted: “I really hate this position. I’d rather just have a DQ, it’s way more satisfying. But we’re just going to have to wait and see. “Fingers crossed.’’ Uncrossed now.

Last week, Bishop-Nriagu had told the Star: “Rio was really hard. It was a dark space for me, for sure. It followed me for months.’’

This result might be darker still.

She injured her left hamstring a week ago at the Canadian team camp in Gifu, Japan. Throughout this year, she’d dipped under the two-minute barrier on four occasions.

“Seven days ago, I was in medal shape,’’ Bishop-Nriagu told The Canadian Press exclusively later. “I was in Canadianrecord shape. And then everything came to a screaming halt. Sadly, that’s what sport is. You’ve got to come to these Games at 100 per cent and I wasn’t 100 per cent.

“And that’s what’s frustrating. And not at all how I perceived my redemption from 2016. “It’s really hard.’’ Canadians Madeleine Kelly (2:02.39) and Lindsey Butterworth (2:02.45) also failed to move through.

In the absence of the Banned Three — and without them, the top six performers this season have less than a second between them — all the main contenders advanced as expected. Only two of the women, Goule and Britain’s Jemma Reekie, went under two minutes Friday.

Among those who advanced were Rose Mary Almanza, of Cuba, who has shaved more than a second off her personal best at age 29, reigning world champion Halimah Nakaayi, from Uganda, world silver medallist Raevyn Rogers, from the U.S., and 19-year-old American Athing Mu, who has posted the fastest time in the world this year, 1:56.07.

The Americans, with Ajeé Wilson (2:00.02) also in the advancing mix, have visions of gold, silver and bronze dancing in their head.

The U.S. has not won a medal in the women’s 800 since 1988 and gold-less since 1968.