Serena Williams is one of the most dominant sportswomen of all time - across any sport. However, even in a sport where men and women earn similar prize pots for many events (including Wimbledon), she is still out-earned 3-1 by Roger Federer.
And that's just the start of the story for many professional athletes, as the gap between earnings for men and women increases steadily.
There are, however, some sports where men and women earn similar amounts - many athletics events among them - but are things changing for the better?
Take a look at our Money in Sport infographic below, and see how the situation stands for some of the most iconic sportsmen and women all over the world.
