Caster Semenya went to the Court of Arbitration for Sport (CAS) on Monday to challenge proposed rules that could force her to lower her testosterone levels.
The Olympic 800m champion made no comment as she arrived at the court in Lausanne for the start of a week-long hearing that could define the rest of the 28-year-old’s career.
The South African government has said the rules set out by track and field’s governing body, the International Association of Athletics Federations (IAAF), specifically target Semenya and has called them a “gross violation” of her human rights.
The controversial measures would force so-called “hyperandrogenic” athletes or those with “differences of sexual development” (DSD) to take drugs to lower their testosterone levels below a prescribed amount if they wish to continue competing.
The rules were to have been introduced last November, but have been put on hold pending this week’s hearings.
IAAF President Sebastian Coe, arriving at the court, said: “Today is a very, very important day.
“The regulations that we are introducing are there to protect the sanctity of fair and open competition.”
The chief advocate for Athletics South Africa (ASA), Norman Arendse, said Semenya would give evidence.
Arendse says: “The whole week is going to be important. Obviously, the evidence will be evaluated and assessed at the end of the process this week, so today this is the start.”