Novak Djokovic has set a new record of 311 weeks as world No 1, surpassing the record he had jointly held with Roger Federer.
Djokovic, 33, also has another of Federer's records in his sights after winning his 18th Grand Slam at last month's Australian Open, two shy of the Swiss legend's mark.
With Federer turning 40 in August, the Serb has time on his side. He is also a year younger than Rafael Nadal, who also has 20 majors.
"It really excites me to walk the path of legends and giants of this sport," said Djokovic, in a statement released by the ATP.
"To know that I earned my place among them by following my childhood dream is a beautiful confirmation that when you do things out of love and passion, everything is possible."
Djokovic has spent 88 weeks at world No 1 across two different stints.
He reclaimed the top ranking from Nadal in February 2020 and finished as year-end No 1 for the sixth time, tying the record set by Pete Sampras.
"Novak's many achievements in tennis are nothing short of extraordinary," said ATP chairman Andrea Gaudenzi. "Among them this record may stand as his single most impressive ... Novak has redefined in our sport."
Federer, who returns to action in Doha this week after more than a year out to recover from two knee operations, slipped out of the top five on Monday to sixth. His place was taken by Stefanos Tsitsipas.
Djokovic first became reached the summit of the ATP rankings at the age of 24 on July 4, 2011, the day after winning Wimbledon for the first time.
Only a six-month injury absence in 2017 saw his ranking plunge, all the way to 22 the following summer.
He was back at the top again by November and with the exception of November 2019 until January last year, when Nadal reclaimed pole position, he has been rock solid.
Few would bet against Djokovic, who in 2016 was the first man to break the $100 million prize money barrier, ending his career with more Slams than Federer and Nadal.
In head-to-heads, he leads Federer 27-23 and has won all six of their last meetings at the majors, including 2019's epic Wimbledon final where he saved two match points.
