Novak Djokovic has hired a new coach -- longtime friend and rival Andy Murray, who retired from competitive tennis this summer. Djokovic split with coach Goran Ivanisevic after six years earlier this summer, and he's counting on Murray to help him prepare ...

Novak Djokovic cracked a hilarious joke after the news broke out of him adding Andy Murray for the Australian Open as he referenced to one of the Briton's post that came just hours after he retired.

Djokovic had been without a full-time head-coach since he ended his five-year partnership with Goran Ivanisevic back in March. During the off-season, there had been rumblings about the world No. 7 hiring a big name as his coach.