Novak Djokovic began the 2021 tennis season on 2 February 2021, with the start of the ATP Cup. In the 2021 season, Djokovic became the second male player in tennis history to win Grand Slam tournaments on three different surfaces (clay, grass and hard court) in the same calendar year, following Rafael Nadal in 2010. He has won four tournaments, three of them Grand Slams: the Australian Open, the French Open, and the Wimbledon Championships. He has also won the Belgrade Open, an ATP 250 event and reached his first final in a doubles tournament since 2010. During this season, Djokovic surpassed Roger Federer's record number of weeks spent with the ATP No. 1 singles ranking, and tied Federer and Nadal's record total of Grand Slam men's singles titles at 20.