Swiss Supreme Court reversed ruling that had temporarily suspended IAAF regulations preventing the double Olympic champion to defend her 800m world title in Doha
Caster Semenya has won 31 straight 800m races since 2015.
There have been two appeals against the IAAF rules that stop her from competing without medication.
But the reinstatement of eligibility regulations, after the Swiss Federal Supreme Court ruling, means she can't continue to run at this distance without lowering her testosterone levels.
So, what are the options for the South African?
The International Association of Athletics Federations (IAAF) believes the ruling has created "much needed parity and clarity for all athletes as they prepare for the World Championships in Doha this September."
In a statement, they added they "will maintain (their) position that there are some contexts, sport being one of them, where biology has to trump gender identity.
"The DSD (Differences in Sex Development) Regulations are a necessary, reasonable and proportionate means of protecting fair and meaningful competition in elite female athletics."
When asked in May if Semenya would consider taking testosterone-lowering medication, her response was clear.
"Hell, no," she said to Al-Jazeera. She has repeatedly refused using medication to satisfy the IAAF rules.
This means she cannot continue to compete in the 800m.
It takes at least six months of testosterone treatment in order to satisfy the rules so, under the current situation, Semenya will not be able to compete her favourite discipline at the World Championships.
However, the latest Swiss court ruling is not final.
In a statement Dorothee Schramm, the lawyer leading Semenya's appeal, said:
"The judge's procedural decision has no impact on the appeal itself."
"We will continue to pursue Caster's appeal and fight for her fundamental human rights. A race is always decided at the finish line."
The release date for this decision is not made public.
Semenya's first task is simply to wait for this final ruling from the Swiss Federal Supreme Court.
The rules mean Semenya can't run in any event from the 400m to the mile (1.6km) without lowering the amount of testosterone in her blood.
The next distance would be the 3,000m.
She entered to race this distance at the Prefontaine Classic Diamond League meeting in June initially.
But eventually was able to compete in the 800m after a court ruling.
Her personal best at this distance is listed as 9:36:29 and dates back to March 2017.
The flat 3km is not an Olympic discipline. The 3,000, steeplechase is in the programme and the qualification time is 9:30 dead.
The 5,000m is another option for her, and her PB of 16:05.97 for that event was set in April 2019.
The Tokyo 2020 entry standard for the 5km is 15:10.00.
Semenya's commitment to other distances is still unclear.
Back in May she said:
"I'll always run 800 metres …The 800 metres is my calling, I believe in it. I can't be forced to switch races, I'll switch when I want to switch races. No man can tell me what to do."
Semenya won the 2,000m on 11th June at the Meeting de Montreuil near Paris, afterwards saying she could run any distance if she was unable to continue at 800m.
It could mean updating her social media accounts. Her Twitter handle is @Caster800m.
A tweet from 30 July 2019, the day of the release of the new Swiss court ruling, potentially hints at a new direction.
Semenya has repeatedly expressed her opposition to taking medication having been forced to do so from 2010 to 2015.
Among the revelations in the report were that the IAAF advanced the position that women like Semenya who have an XY chromosome pair were "biological males".
Semenya said, "The IAAF used me in the past as a human guinea pig to experiment with how the medication they required me to take would affect my testosterone levels.
The IAAF welcomed the full release of the report, saying, "The IAAF considers that the DSD regulations are a necessary, reasonable and proportionate means of protecting fair and meaningful competition in elite female athletics, and CAS agreed."
IOC president Thomas Bach expressed his sympathy for Semenya back in May and admitted the issue was "extremely delicate and extremely difficult".
Her main rival over 800m, Burundi's Rio 2016 silver medallist Francine Niyonsaba, told Olympic Channel that the IAAF proposals were "about discrimination".
Like Niyonsaba, Rio 2016 bronze medallist Margaret Wambui may also be affected by the ruling regarding testosterone levels.
"I am very disappointed, I don't feel even like going on with the training because you don't know what you are training for," she told AFP in May.