The Women's Tennis Association has announced a long-term partnership with Mercedes-Benz which has the potential to be the largest in women's sport. The German car manufacturer will become the premier partner of the WTA and pour $50m (£37.5m) per year into women’s tennis for up to 10 years. Equal prize money was one of the key goals when the WTA was founded in 1973. American tennis great Billie Jean King, who founded the WTA and was its first president, said the deal shows the tour "continues to lead the way in women's sport". "Equal prize money is so important and sends a really strong message.