The Court of Arbitration for Sport will hold a landmark hearing this week regarding Olympic athlete Caster Semenya's case against the world's athletics governing body's stance on her sexuality.
The International Association of Athletics Federations had proposed forcing athletes with different levels of sexual development to medically lower their testosterone levels for fairer competition.
The South African 800-meter star would be affected by such rules and has challenged the plan, saying it goes against gender equality.
The proposed rules were scheduled to take effect last November, but have been put on hold pending the week-long hearing which begins Monday.
The ruling is expected to come out near the end of next month.