Rafael Nadal will return to the world number one spot next Monday.
The Spaniard will take the ranking from Andy Murray after Roger Federer withdrew from the Cincinnati Masters due to a back injury.
The Wimbledon champion was the only challenger for the top spot, but he suffered the problem during his defeat to Alexander Zverev in the Rogers Cup final.
Nadal, who won his 15th Grand Slam crown at the French Open earlier this year, has not held the number one ranking since July 2014.
Murray ruled out competing in Cincinnati last week due to his ongoing hip injury.