Caster Semenya will not need to take testosterone-reducing medication to compete after a Swiss court temporarily suspended a new IAAF ruling.
The Olympic 800m champion, 28, last month lost her challenge to the Court of Arbitration for Sport (CAS) against the implementation of a restriction on testosterone levels in female runners.
The ruling would have affected women competing from 400m to the mile.
“I hope following my appeal I will once again be able to run free,” she said.
“I am thankful to the Swiss judges for this decision.”
Following the decision by CAS, the South African took her appeal to the Federal Supreme Court of Switzerland, citing the need to defend “fundamental human rights”.
Her legal representative Dr Dorothee Schramm said: “The court has granted welcome temporary protection to Caster Semenya.
“This is an important case that will have fundamental implications for the human rights of female athletes.”
In a statement to BBC Sport, the Federal Supreme Court of Switzerland said it had “super-provisionally instructed the IAAF to suspend the application of the ‘Eligibility Regulations for the Female Classification for athletes with differences of sex development’ with respect to the claimant, until the decision on the request for issuance of provisional measures”.
It added: “At present, it is not known when the Swiss Federal Supreme Courts will issue an interlocutory order concerning these provisional measures.”
The IAAF said it had yet to receive notification of the new decision from the Swiss court.
In its initial judgement CAS found that the new rules proposed by the IAAF – athletics’ world governing body – for athletes with differences of sexual development (DSD) were discriminatory, but concluded that the discrimination was “necessary, reasonable and proportionate” to protect “the integrity of female athletics”.