Novak Djokovic has admitted he is “sad” that most of his long-term rivals have retired from tennis. The 24-time Grand Slam winner namechecked Andy Murray, Roger Federer and Rafael Nadal before appearing in an exhibition match in Buenos Aires to mark Juan Martin del Potro’s retirement.

Novak Djokovic took time away from the practice court to visit the Qatar Grand Prix and was given a dressing down by new coach Andy Murray on social media

Djokovic admitted that his phone call with Murray caught the Scot "a little off guard" but stressed that the pair "connected really fast". The 37-year-old is said to have only taken a few days to agree to the role, less than four months after retiring at the Paris Olympics.

The Scot shocked the tennis world last week as he announced he will coach the 24-time Grand Slam winner in one of the most sensational appointments in the sport's history.