Paris — Rafael Nadal has described his climb back to the world No1 spot for the first time in three years as "unbelievable".
The Spaniard last topped the men’s charts in July 2014.
His latest position was confirmed by the Association of Tennis Professionals (ATP) rankings released on Monday.
The 31-year-old, who won his 15th Grand Slam title in 2017 at Roland Garros, deposes Britain’s Andy Murray, who withdrew from the tournaments in Montreal and Cincinnati with a hip injury.
Nadal, who has spent 141 weeks in the top spot, has struggled with knee injuries since first becoming No1 in August 2008 after a Cincinnati semifinal run. He doubted that he could regain the No 1 spot after so many years.
"Being No1 after all the things that I have been going through the last couple of years is something unbelievable," he said.
Nadal, knocked out in the Cincinnati quarterfinals last week by Australian Nick Kyrgios, had slipped to as low as 13th in the ATP rankings midway through 2015.
ATP executive chairman and president Chris Kermode hailed Nadal’s path back to the top spot. "It shows incredible dedication and longevity, and we congratulate him on this amazing achievement."