Nole is a Serbian professional tennis player. He is currently ranked as world No. 1 by the ATP. Djokovic has been No. 1 for a record total of 354 weeks, and has finished as ATP Year-End No. 1 on a record seven occasions. He has won a joint record 20 Grand Slam men's singles titles, including a record nine Australian Open titles. Overall, he has won 86 ATP singles titles, including a record 37 Masters events. Djokovic is the only man in the Open Era to achieve a double career Grand Slam and complete a non-calendar year Grand Slam. He is also the only player to complete the career Golden Masters on the ATP Tour, which he has done twice.

Djokovic began his professional career in 2003. At age 20, he disrupted Roger Federer's and Rafael Nadal's streak of 11 consecutive majors to win his first Grand Slam title at the 2008 Australian Open. By 2010, Djokovic also separated himself from the rest of men's tennis to join Federer and Nadal in the Big Three, the group of three players who have dominated men's tennis for more than a decade. In 2011, Djokovic was ranked No. 1 for the first time, winning three out of four majors and a then-season record of five Masters events. He remained the best player in men's tennis for the rest of the decade, leading the tour in major and Masters's titles, and winning four out of his five titles at the ATP Finals consecutively from 2012 through 2015. After four consecutive year-end finishes at No. 3 through 2010, Djokovic finished No. 1 for six years and No. 2 for three years in the next decade.

Djokovic had another career year in 2015, reaching fifteen consecutive finals, including all four major finals and eight Masters finals, winning three majors and a season-record of six Masters events as well as the ATP Finals. The following year, he won the 2016 French Open to complete the first and only non-calendar year Grand Slam in the Open Era and his first career Grand Slam. He became the first man since Rod Laver in 1969 to hold all four major titles at once and the only one in history to do so on three different surfaces.

Representing Serbia, Djokovic led the Serbian national team to their first Davis Cup title in 2010 and to the inaugural ATP Cup title in 2020. Moreover, he won the bronze medal for Serbia at the 2008 Beijing Olympics. Djokovic has won the Laureus World Sportsman of the Year award four times (2012, 2015, 2016, 2019), the BBC Sports Personality World Sport Star of the Year award in 2011 and the L'Équipe Champion of Champions award in 2021. He is also a recipient of the Order of St. Sava, the Order of Karađorđe's Star, and the Order of the Republika Srpska. Beyond competition, Djokovic was the former ATP player council president and is also an active philanthropist. In August 2020, Djokovic and Vasek Pospisil announced the formation of the Professional Tennis Players Association as the first player-only association in tennis, citing the need for players to have more influence on the tour and advocating for better prize money structure for lower ranked players.