Former world number one Novak Djokovic suffered a surprising defeat by world number 58 Hyeon Chung in the fourth round of the Australian Open. The 21-year-old South Korean defeated Djokovic 7-6, 7-5, 7-6 to reach the quarter-final stage of a Grand Slam for the first time in his career. Djokovic is the most successful player in the history of the tournament, having won six times in Melbourne. But he has not won a Grand Slam since the 2016 French Open having struggled with injuries and poor form. Djovick was hampered by the elbow injury which had kept him out of tennis for six months after Wimbledon.