When Margaret Court walked into the locker room at the close of the 1973 French Open, Martina Navratilova tried not to gawk. Court was a figure of awe, the most successful player in the history of women’s tennis. Navratilova was an ungainly teenager competing in her first international tournament. When the player known as ‘the Arm’ said hello, young Martina was “thrilled” to have been recognised. Margaret knew class when she saw it, acknowledging Navratilova as “the wave of the future”.

In due course, the up-and-comer and the champ faced each other across the net...