Caster Semenya has 30 days to challenge the decision to dismiss her appeal against restrictions being placed on female athletes with elevated levels of testosterone - but the timescale for choices over her career direction is far shorter.
On Wednesday, the Court of Arbitration for Sport rejected the double Olympic 800-metres champion's bid to throw out rules introduced by the International Association of Athletics Federations (IAAF) to force those with differences of sexual development (DSDs) to take testosterone blockers if they want to run in world-class races from 400 metres to a mile.
The 28-year-old South African can appeal the CAS ruling at the Swiss Federal Tribunal within 30 days, and she might well take that option. Some observers suggest she might then contemplate taking the case to the European Court of Justice.
But in the meantime, the IAAF says that if she wants to defend her 800m title at the world championships in Doha in September, Semenya needs to start taking medication immediately to show significant change within seven days and then maintain it below a set level continuously.
The IAAF also quickly dismissed CAS's advice that the restrictions should not apply yet to the 1,500m, where Semenya won bronze at the last world championships in London two years ago.
In other words, if Semenya wants to race her preferred distances, she needs to start taking the suppressant medication right away.
She has been through this process before, when the IAAF originally introduced its restrictions in 2011. Semenya then did take a course of hormone-suppressing drugs and her performances slumped for several years.
She finished in the silver medal position at the 2012 Olympics - later upgraded to gold after Russian winner Mariya Savinova was stripped of the title for doping - with a time nearly two seconds slower than she had run when she was a teenage winner at the 2009 world championships in Berlin.
But when a court challenge lifted restrictions four years ago, Semenya quickly returned to dominate the 800m event in devastating fashion.
If she now decides, at the age of 28 and with the battle against the IAAF so central to her life, not to go down the medication route, she could still race over 5,000 metres, where the IAAF says its research shows the impact of high testosterone levels is limited.
It is a relatively common progression for middle-distance athletes to step up to 5,000 and 10,000m as they approach their 30s. At last weekend's South African championships, Semenya ran the 1500m and - for only the second time competitively - the 5000m, winning both events.
Her time of 16:05.97 in the 5000m was well outside the qualifying standard for the world championships, although she would have until Sept. 6 to cut it down to 15:22.00. Tirunesh Dibaba's 11-year-old world record for the distance is 14:11.15.
The huge response to Wednesday's decision, both for and against, as well as CAS's published reservations about the implementation of the new restrictions, suggest this is far from the end of the story.
When Semenya blasted to the world title as a teenager in 2009, she was almost immediately embroiled in questions about verification of her sex.
Ten years on, that debate continues, and Semenya's decision - and that of other women in a similar situation - on what she does next will be watched by fans of athletics and far beyond.