The South African runner, Caster Semenya, is challenging controversial plans to limit genetically high levels of testosterone in some female athletes that are said to give them an undue performance advantage.
The sport's international governing body, the International Association of Athletics Federations (IAAF), says it wants to make races fairer by getting athletes with hyperandrogenism to take medication to lower their male hormone level, six months before they compete.
Semenya's lawyers will argue in Lausanne, Switzerland, that this would be discriminatory, and that the world and Olympic champion's genetic condition should instead be celebrated.
Academics have questioned the science behind the IAAF's plans.
Semenya has dominated the 800m event for the past decade.
The IAAF last Wednesday denied it will class any athlete with "differences of sexual development" (DSD) as male.
"Ms Semenya is unquestionably a woman," said Semenya's lawyers in a statement on Thursday.
"She is a heroine and an inspiration to many people around the world.
Ms Semenya is fighting for her right to run without being required to undergo unnecessary medical intervention - she is fighting to run free."