Billie Jean King’s 1973 match was about social change. The upcoming Sabalenka-Kyrgios event – with its rules tweaks and its participants’ questionable politics – may leave women’s tennis worse off.

Nick Kyrgios believes few male players would accept the chance to face a top woman as the maverick Australian prepares to take on women’s world number one Aryna Sabalenka in a “Battle of the Sexes” ...