Caster Semenya had a stellar year on the track and is looking ahead to the 2020 Olympics. Photo: Darren England/EPA

LONDON – Tennis great Martina Navratilova has come to the defence of Olympic 800 metres champion Caster Semenya ahead of next week's landmark hearing on proposed rules that aim to restrict testosterone levels in female athletes.

The International Association of Athletics Federations (IAAF) has proposed rules that would force so-called "hyperandrogenic" athletes or those with "differences of sexual development" (DSD) to medically lower their testosterone levels below a prescribed amount.

Track and field's global governing body wants to introduce the rule changes in order to promote what it says will be fairer competition between all female athletes.

But South Africa middle-distance star Semenya, the most high-profile athlete who would be affected by such an alteration to the rule book, is challenging the legality of the IAAF's proposals in a case which will be heard at the Court of Arbitration (CAS) in Lausanne from Monday.

Significantly, the change would only apply to female athletes competing in distances from 400 metres to a mile – a point highlighted by 18-time Grand Slam singles champion Navratilova in a column Britain's Sunday Times newspaper.

"Leaving out sprints and longer distances seems to me to be a clear case of discrimination by targeting Semenya," Navratilova wrote.

"And can it be right to order athletes to take medication? What if the long-term effects proved harmful?

"Semenya's case will come up tomorrow before the Court of Arbitration for Sport. It is expected to last a week and the outcome is expected by March 29. I hope she wins."

Semenya, the Olympic 800m gold medallist at both the London and Rio Games, is also a three-time world champion.

AFP