Novak Djokovic says his rivalry with Andy Murray has "one final chapter" after his long-time adversary joined him as his coach for the upcoming Australian Open.Murray - Britain's greatest ever player - retired after this summer's Olympics at the age of 37 after finally admitting defeat in his battle against his body.Many in the game expected the Scot would one day return to tennis and become a coach, particularly due to his love of the sport, hard work and his tactical acumen.

Novak Djokovic says his rivalry with Andy Murray has "one final chapter" after his long-time adversary joined him as his coach for the upcoming Australian Open.Murray - Britain's greatest ever player - retired after this summer's Olympics at the age of 37 after finally admitting defeat in his battle against his body.Many in the game expected the Scot would one day return to tennis and become a coach, particularly due to his love of the sport, hard work and his tactical acumen.