Novak Djokovic hailed the retiring Roger Federer as one of the greatest athletes of all time and said he would leave a lasting legacy for the world of tennis. The 41-year-old Swiss great will play competitively for the last time at this week's Laver Cup, turning out for Team Europe alongside Rafa Nadal, Andy Murray and Djokovic - the three biggest rivals of his glittering 24-year career.
