Novak Djokovic is a Serbian professional tennis player. Djokovic has been ranked as the world No. 1 in men's singles by the Association of Tennis Professionals (ATP) for a record 428 weeks, finished as the year-end No. 1 a record eight times, and has been ranked No. 1 at least once in a year for a record 13 different years. He has won 101 ATP Tour–level singles titles, including a record 24 majors (among which a record ten Australian Open titles), a record 40 Masters, a record seven year-end championships, and an Olympic gold medal. Djokovic is the only man in tennis history to be the reigning champion of all four majors at once across three different surfaces. In singles, he is the only man to achieve a triple Career Grand Slam, and the only player to complete a Career Golden Masters, a feat he has accomplished twice. Djokovic is the only player in singles to have won all of the Big Titles over the course of his career.
Djokovic began his professional career in 2003. In 2008, at age 20, he disrupted Roger Federer and Rafael Nadal's streak of 11 consecutive majors by winning his first major title at the Australian Open.