Novak Djokovic is currently 401 weeks as the World No. 1, which is a record for any singles player, male or female.
The Serb was assured of a record-extending eighth year-end finish at the top of the rankings after winning his first match at the ATP Finals.
Djokovic became the World No. 1 for the first time in his career after winning Wimbledon in 2011 by defeating Rafael Nadal in the final. His stay lasted 53 weeks before being dethroned by Roger Federer the following year. However, he reclaimed the ranking from the Swiss and finished 2012 as the World No. 1.
Djokovic's second spell as World No. 1 lasted 48 weeks before Rafael Nadal overtook him in October 2013. The Serb dethroned the Spaniard by winning Wimbledon in 2014 and this time, he enjoyed his longest spell as World No. 1.
He was at the top of the rankings for 122 weeks in a row before being surpassed by Andy Murray at the 2016 ATP Finals. Djokovic reclaimed the No. 1 spot almost exactly two years later on November 5, 2018, before being dethroned by Nadal at the same time in 2019.
He once again reclaimed his ranking in February 2020 and was at the top for seven weeks until the rankings were frozen due to inactivity owing to the COVID-19 pandemic. Once the sport resumed, Djokovic continued to be the World No. 1 until February 2022 when Daniil Medvedev surpassed him. During this time, he broke Roger Federer's record for the most number of weeks at the top of the rankings.
The Serb lost the No. 1 ranking in 2022 but regained it in 2023 after winning the Australian Open. In February, he set a new record for the most number of weeks at the top spot by any player, male or female, surpassing Steffi Graf's tally of 377 weeks.
Djokovic had a battle with Carlos Alcaraz for the No. 1 ranking, which he eventually won after his first win at the ATP Finals in Turin. He went on to win the tournament and entered a historic 400th week as the World No. 1.
The Serb is currently in his 401st week at the top of the rankings and will hold the position until at least the Australian Open in 2024.
Novak Djokovic won seven titles in 2023

Novak Djokovic has enjoyed an impressive 2023 season, winning 56 out of 63 matches with seven titles to his name.
The Serb reached the final of all four Grand Slams, winning three of them. He also won the ATP Finals for a record seventh time while clinching two Masters 1000 titles in Cincinnati and Paris.
Very recently, he represented Serbia in the knockout stages of the Davis Cup and helped them reach the semifinals, where they were beaten by eventual champions Italy.
How did Novak Djokovic meet Jelena Ristic? All about the most admired couples in tennis