Alistair and Jonny Brownlee are the most loyal of friends and yet the toughest of rivals. They have the capability of bringing the best - and at times the worst - out of each other. In Rio 2016, Alistair will be aiming to become the first triathlete to successfully defend their Olympic title, while younger brother Jonny's target is to improve on the bronze medal he earned at London 2012. In the build-up to the Games, Tom Fordyce speaks to the brothers as he looks into what it is about their relationship that makes them so unique and their achievements so extraordinary.