Japan's Kei Nishikori, who has secured a spot in the season-ending ATP Finals, jumped two places to No. 9 in the ATP rankings on Monday.
Nishikori broke into the top 10 for the first time since August 2017, when he suffered a season-ending wrist injury. Paris Masters runner-up Novak Djokovic returned to No. 1 for the first time in two years.
The 28-year-old Japanese qualified for the Nov. 11-18 season finale in London following the withdrawal of Argentina's Juan Martin del Potro due to a right knee injury. Nishikori and Djokovic are among the eight leading singles players to compete in the ATP Finals.
In January, former world No. 4 Nishikori returned from a five-month layoff due to a right wrist injury. He fell to 39th in April but will finish the year in the top 10, having reached the quarterfinals or better in his last six events.
This season, Nishikori finished runner-up at the Monte-Carlo Masters, the Rakuten Japan Open and the Erste Bank Open. He made the quarterfinals at Wimbledon and semifinals at the U.S. Open, his best result at a Grand Slam this year.
Before making his comeback on the ATP World Tour, he claimed the RBC Tennis Championships of Dallas in February, an event on the second-tier Challenger Tour.