Unique gathering of former world 's No.1 tennis players at Wimbledon . Event to mark the 40th aniversary of WTA official foundation in 1973 . Tributes paid to first WTA president Billie Jean King . Current champion Serena Williams takes center stage .
Unique gathering of former women 's No.1 tennis players at Wimbledon . Event to mark the 40th aniversary of WTA Tour foundation in 1973 . Tributes paid to first WTA president Billie Jean King . Current No.1 Serena Williams took center stage .