The most important race of Caster Semenya's life has kicked off, except this time nobody knows where the finish line is. Nor even in what direction she will go to get there. And that could be a problem because the 28-year-old, who has become the most publicly prodded athlete since she burst onto the international scene at the 2009 world championships, is surely approaching the closing stages of her illustrious career.
Time is not on Semenya's side. One way or another, the decision by the Court of Arbitration for Sport (CAS) to dismiss her challenge of the world athletics governing body's new regulations for female eligibility looks set to cost her on the track.
The International Association of Athletics Federations (IAAF) requires all female athletes with differences of sex development (DSD) who possess male XY chromosomes to take medication to lower elevated levels of naturally occurring testosterone if they compete in all races from the 400m to the mile.
Those are the same events in which Semenya is world class, although the IAAF has also thrown in the 400m hurdles and pole vault.
The CAS admitted the policy was discriminatory, but accepted that this was necessary. "The imperfect alignment between nature, law and identity is what gives rise to the conundrum at the heart of this case," it wrote in its executive summary.
The decision has been roundly criticised, largely because the IAAF's regulations were based on flawed science.
LEGAL OPTIONS
One would assume that an appeal against the judgment would have a reasonable chance of success, but this is not guaranteed. After all, if the IAAF and CAS can get it wrong, why not others?
Semenya's lawyers have 30 days from the date of the judgment to submit an appeal to the Swiss Federal Tribunal, the highest court in Switzerland.
That process, according to some people in the know, could take six months.
Even if Semenya were to win, that's too late for the 2019 world championships in Doha, where she is scheduled to defend her 800m crown. The event kicks off on September 28.
She and Kenya-born Wilson Kipketer, who switched allegiance to Denmark, are the only two people in history to have won three 800m world championship titles.
Semenya's bid for an unprecedented fourth, if she chooses to go for it, will require her to take suppressants.
In the Olympic arena she is tied alongside four men as the most prolific 800m champions with two crowns apiece - Kenya's David Rudisha, Kiwi Peter Snell, American Mal Whitfield and Briton Douglas Lowe.
The Tokyo games next year offer her a chance of charting new territory once again.
But should she lose in the Swiss supreme court, that dream may become a bit more difficult. Legally, she could then approach the European Court of Human Rights in Strasbourg, France.
Time is ticking.
ON MEDICATION
It's not a given that Semenya will take the medication, especially after her legal campaign that she be allowed to compete freely.
If she chooses to take it, she will have to start when the regulations kick in on Wednesday.
The CAS envisaged that athletes would reduce testosterone by taking "conventional oral contraceptives" and two of the three judges "had regard to the possible side effects" of such medication.
However, the World Medical Association (WMA) has called on doctors to boycott the decision by not dispensing suppressants to female athletes with high testosterone levels.
"We have strong reservations about the ethical validity of these regulations," WMA president Dr Leonid Eidelman said in a statement. "They are based on weak evidence from a single study, which is currently being widely debated by the scientific community.
"They are also contrary to a number of key WMA ethical statements and declarations, and as such we are calling for their immediate withdrawal."
But what would happen if Semenya were to take the medication?
She took suppressants from 2010 until 2015 when the CAS suspended the IAAF's previous regulations for lack of scientific evidence.
DSD athletes will have to keep testosterone levels below 5nmol/l, which is more than double the average of elite female athletes. But it's half the limit that it was under the old IAAF regulations, which makes it more onerous for these athletes to comply with.
On the medication, Semenya won 800m silver at the 2011 world championships and 2012 Olympics, although both were upgraded to gold after the winner, Russian Mariya Savinova, was stripped of her title for doping. But Semenya's best times in the medication years are slower than when she has run freely.
Semenya ran the 800m in 1:55.45 in 2009, but two years later did a best of 1:56.35, her fastest time of the medication era.
In 2014 she failed to break two minutes.
Her detractors have used this as proof that she benefits from her condition, but they don't take into account the bad knee injury she struggled with from 2012 to 2014.
Since the regulations were suspended in 2015, Semenya has improved her best times gradually each year and her fastest 800m - before Friday's Diamond League meet in Doha - stood at 1:54.25, the fourth-fastest of all time.
That's almost a full second slower than the 1:53.28 world record owned by Jarmila Kratochvílová and still a way off Pamela Jelimo's 1:54.01 African mark.
For all that higher levels of testosterone allegedly give her an unfair advantage, the fact is that non-DSD female athletes have been closing the gap on her at championship races.
At the 2009 world championships her lead was 2.12% and by 2017 it had shrunk to 1.29%.
How Semenya would perform while taking medication to push testosterone to levels lower than she has in the past is a matter of speculation.
OFF MEDICATION
If Semenya chooses not to take medication, she will have to switch events to carry on competing.
Though the 400m is probably her strongest event outside her favourite 800m, she's probably too slow for the 200m.
She definitely lacks the speed for the 100m.
That means she would have to look at the longer distances.
In terms of the Olympic roster, after the 1,500m comes the 5,000m, which she ran at the South African championships in Germiston last weekend.
She comfortably beat defending champion Dominique Scott, but her 16:05.97 winning time is way off the best in the world.
Consider this: last year Semenya was ranked number one in the 800m, fourth in the 400m and ninth in the 1,500m.
Her 5,000m time would have placed her 354th in 2018; she may be able to improve a lot, but the challenge facing her in the 5,000m and longer events is even greater than the disadvantage she already faces in the 1,500m.
THE 1,500m
The CAS ruling offered Semenya possible respite in the 1,500m by noting "the paucity of evidence to justify the inclusion" of the 1,500m and the mile. Will the IAAF do the gentlemanly thing and remove these two events on its own initiative? The federation had yet to respond to the Sunday Times on this question.
Let's say it does. It's still no plain sailing for Semenya.
Semenya bagged a gold-bronze double at the last world championships, in London in 2017, winning the 800m and snatching third place in the 1,500m. She delivered a strong kick on the final lap to finish in 4:02.90 to knock British star Laura Muir off the podium by seven-hundredths of a second.
At the 2018 Commonwealth Games in Gold Coast she won gold in both events, taking the 1,500m in 4:00.71.
Soon afterwards she dipped under four minutes to lower her South African record to 3:59.92.
But at the 2018 Diamond League meet in Lausanne - the same city that houses the CAS - she was handed a sobering lesson in 1,500m reality.
She went 4:00.44 against a world-class field and ended sixth. US winner Shelby Houlihan crossed the line in 3:57.34 and even fifth-placed Rababe Arafi of Morocco's 3:59.15 was out of reach.
This is not to say Semenya can't go faster in the 1,500m, but with her bulk compared to the smaller frames in the field it seems like a mountain to climb. Unless she proves she can go faster - and this is an event in which several of the world's best have peaked by the age of 26 - her best chance is hoping that the frontrunners go out slowly enough to bring her kick into play.
And this best-case scenario depends on the IAAF removing the 1,500m from the regulations.
What would happen if Semenya were to confound everyone and become a force at 5,000m?
The IAAF regulations were described by the CAS as a living document, to which presumably it can add and remove as it likes. So if she were to be successful in new events, it could end up being a case of damned if she does and damned if she doesn't.
If Semenya is a target, as the IAAF critics believe, then she could be hounded for the rest of her career...