Cape Town - Tennis icon Billie Jean King has joined the wave of support for her friend and double 800m Olympic champion Caster Semenya.
Semenya is appealing a decision from the IAAF at the Court for Arbitration of Sport (CAS) in Switzerland this week.
The proposed IAAF ruling would see Semenya forced to lower her testosterone levels in order to promote what it says will be "fairer competition between all female athletes".
READ: SA's golden boy Le Clos leads way in #HandsOffCaster movement
King took to Twitter to defend and back Semenya, writing: "Semenya is unequivocally female... I stand behind her and hope she prevails."
Last year October, Semenya received the Wilma Rudolph Courage Award from the Women's Sports Foundation and King in New York.
King, 75, notched up no less than 12 grand slam singles titles, which when added to her women’s and mixed doubles titles, inflates to 39.