Billie Jean King is, once again, fighting on behalf of women.

The tennis legend is speaking out against Republicans in the US Congress who she says are waging 'an epic battle' against women’s health care choices.

'I'm so appalled by what we’re seeing in Congress right now,' King wrote in an email this week. 'First, House Republicans held a hearing on women's access to birth control coverage that included a panel with five men and no women. Then they changed their own rules and refused to televise testimony from women’s right advocate Sandra Fluke.'

King, 68, is working with the Democratic Congressional Campaign Committee and encouraging people to sign the petition One Million Strong Against the Republican War on Women.

'Republicans want to silence women but I refuse to sit on the sidelines,' King wrote. 'You may know me from my tennis career, but some of my biggest victories came off the court--for fairness, equality and progress for women.'

King, winner of six Wimbledon singles titles, became a feminist icon in 1973 when she defeated Bobby Riggs in a televised 'Battle of the Sexes' match in Houston, Tx.

She was the number one female tennis player in the world at the time and took on the challenge from Riggs - a former Wimbledon champion then in his 50s - after Margaret Court had lost to him in a previous match.

Even before that historic match, King had been fighting for women's equality and helped launch a separate tennis tour for female players because the tennis establishment had persisted in treating them as a sideshow with far less prize money.

King said she is speaking out now to send 'Republicans a clear, unmistakable, and powerful message.'