In sport, if you take over from another person who has been injured or who has given up their position, you step into their boots. Michael Kinane, the leading Irish jockey, has turned down the chance to step into Steve Cauthen's boots and ride for Sheikh Mohammed next season. Note: You can say that someone fills another person's boots if they are as successful as them. It is sad that he's gone, but if ever there was a man to fill his boots, it's Kevin Keegan. Compare with step into someone's shoes.