Kei Nishikori claimed the eighth and final entry to the season-ending ATP Finals Saturday when Argentina's Juan Martin del Potro withdrew due to a right knee injury.
Nishikori, ranked ninth in the ATP Race to London, will play in the tournament for the fourth time and will join Novak Djokovic, Rafael Nadal, Roger Federer, Alexander Zverev, Kevin Anderson, Marin Cilic and Dominic Thiem at the Nov. 11-18 event in London.
The 28-year-old Nishikori reached the semifinals at the ATP Finals in his most recent appearance in 2016.
"First of all, I want to wish Del Potro a speedy recovery. He had an amazing year," Nishikori said on Twitter of the world No. 4 who suffered a fractured kneecap at the Shanghai Masters last month.
"Second, I am very excited to join the London field. I started my year with challengers and missed the Aussie Open and Indian Wells. Very proud of the way the year turned out," he added.
In January, Nishikori returned from a five-month layoff due to a right wrist injury. He fell to 39th in the world in April but will finish the year in the top-10.
According to the ATP, Nishikori is only the third player since 1994 to win a Challenger Tour title and go on to qualify for the tour finals in the same season.