Clarifying promised rules on female eligibility, track and field's governing body set a Sept. 1 deadline Wednesday for athletes to pass a gene test for competing at the world championships.

World Athletics said in March that it would require chromosome testing by cheek swabs or dry blood-spot tests for female athletes to be eligible for elite-level events.

The next worlds open Sept. 13 in Tokyo, and Sept. 1 is "the closing date for entries and the date the regulations come into effect," World Athletics said in a statement.

The latest rules update gives certainty for the 2025 championships in an issue that has been controversial on the track and in multiple courts since Caster Semenya won her first 800 meters world title as a teenager in 2009.

Semenya won a ruling at the European Court of Human Rights three weeks ago in Strasbourg, France, amid the South Africa star's yearslong challenge to a previous version of track and field's eligibility rules affecting athletes with medical conditions known as differences in sex development. That legal win came because she did not get a fair hearing at the Swiss supreme court, but it did not overturn track's rules.

World Athletics drew up rules in 2018 forcing two-time Olympic champion Semenya and other athletes with DSDs to suppress their elevated natural testosterone levels to be eligible for international women's events. Semenya refused to take medication.

Now, the Monaco-based track body requires a "once-in-a-lifetime" test for a gene that indicates whether the athlete has a Y chromosome present in males.

"We are saying, at elite level, for you to compete in the female category, you have to be biologically female," World Athletics president Sebastian Coe said.

The governing body is covering up to $100 of the costs for each test with the protocol overseen by its member federations at the national level. Test results should be ready within two weeks.