Caster Semenya is a two-time Olympic and three-time world champion over 800 metres – but further gold medals now depend on her taking hormone-suppressing drugs or changing events.
Defeat in her legal fight against world athletics governing body the IAAF over its controversial rules which will force some female athletes to medically lower naturally-occurring testosterone is set to have major implications for not just her career, but that of others in her sport.
The South African, who has hyperandrogenism, a medical condition characterised by excessive levels of male sex hormones such as testosterone, had argued the rules, which will concern athletes competing in events from the 400m to the mile, were unlawful.
The regulations, announced last April, were designed by the IAAF to combat claims women with higher levels of natural testosterone enjoy an unfair advantage in competition.
Semenya's lawyers, though, branded them "flawed" and "hurtful", while she received support from the likes of the United Nations Human Rights Council and the South African government.
Semenya has said she just wants to "run naturally, the way I was born" – but the Court of Arbitration for Sport has now ruled it would harm the integrity of female athletics to allow her to so.
Born in Ga-Masehlong, a village near Polokwane, in South Africa in January 1991 to parents Dorus and Jacob, Semenya also lived with her grandmother, Maputhi Sekgala.
She played football growing up, but served notice of her prowess on the track when she won the 800m and 1500m at the African Junior Championships in 2009, breaking not only the South African junior record but also the senior mark by clocking one minute 56.72 seconds over the shorter distance.
And she announced her arrival on the global stage in Berlin later that year when, aged 18, she won the world 800m title in 1min 55.45secs.
That victory, though, was overshadowed by speculation over her gender as it emerged she had been ordered by the IAAF to undergo a gender verification test. The governing body came in for fierce criticism over its handling of the case, critics claiming they showed a lack of sensitivity and compassion towards a young athlete in the eye of a storm.
In the 10 years since Semenya has not been able to escape the issue.
She was not cleared to return to international competition until July 2010.
In 2011, the IAAF introduced a limit on the amount of testosterone a female competitor could have in their bloodstream of 10 nanomoles per litre (nmol/L), approximately five to six times over the usual female range for the hormone, meaning Semenya had to take testosterone-suppressing medication to race.
She won silver at the 2011 World Championships in Daegu and the London 2012 Olympics, in times slower than she ran in Berlin, but was later upgraded to gold in both events after Russia's Mariya Savinova was disqualified for doping.
Semenya failed to qualify for the 2013 World Championships.
In July 2015, the Court of Arbitration for sport reversed the IAAF's rule following a case brought by Indian sprinter Dutee Chand, meaning Semenya could compete again without medication.
She failed to reach the final of the World Championships the following month, but the following year stormed to Olympic gold in Rio in 1:55.28. Semenya, who married wife Raseboya in January 2017, lowered that time to 1:55.16 that summer as she took the world title in London, where she also won 1500m bronze.
Last June she clocked a new personal best of 1:54.25, making her the fourth fastest female 800m runner in history, but the bigger battles facing her were away from the track as the IAAF announced its intention to set a limit on how much testosterone female athletes in specific track events, including the 800m and 1500m, can have in their blood stream.
The limit, the key element in the IAAF's proposed 'Eligibility Regulations for Female Classification (Athletes with Differences of Sex Development)', required Semenya to once again take medication to reduce testosterone levels. It was meant to come into force last November, but was postponed as she and Athletics South Africa launched a legal challenge.
On this occasion, Semenya would not emerge victorious.