Novak Djokovic has mocked Andy Murray with an impersonation of the tennis star. Both players get on well off the court, having been two of the best players of their generation over the past 15 years. Djokovic has won a staggering 24 Grand Slam titles throughout his career, a number no other male player in history has been able to reach. And Murray, despite having to compete against the Serb, Rafael Nadal and Roger Federer, has won three crowns. On Monday, the ATP Tour uploaded a clip of Djokovic. He said: “I started thinking about Andy Murray. “Okay. There’s this guy who does [an] impersonatio…