World Number One Novak Djokovic has retained the Men's Singles title in the Australian Open Tennis championships. In Melbourne yesterday, the Serbian defeated Briton Andy Murray in four sets 6-7, 7-6, 6-3, 6-2. 25-year old Djokovic also became the first player to clinch the professional era's hat-trick of Australian Open titles. Overall, it was his fourth Australian crown and sixth Grand Slam title.