Rafael Nadal described as "unbelievable" his climb back to the world number one spot for the first time in three years and confirmed in the latest ATP rankings released on Monday.
The Spaniard, who learned he was going to reclaim the ATP summit a week ago, last topped the men's charts in July 2014.
The 31-year-old Spaniard, who won his 15th Grand Slam title this year 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 No 1 in August 2008 after a Cincinnati semi-final run. He has admitted doubting he could ever regain the number one spot after so many years.
"Being No 1 after all the things that I have been going through the last couple of years is something unbelievable," the Spanish great told the ATP.
Meanwhile, Czech tennis player Karolina Pliskova remained at the top of the Women's Tennis Association rankings released on Monday with 6,390 points, while Spain's Garbiñe Muguruza climbed to the third place from the sixth spot. Romania's Simona Halep, who would have gone to the top had she not lost the Cincinnati Final to Wimbledon champion Muguruza on Sunday, came in second with 6,385 points, reports Efe.
Germany's former number one Angelique Kerber dropped from third to sixth.