Kei Nishikori joked that he wanted Novak Djokovic to retire because he is the most complete player on tour.
"Honestly I sometimes kind of wish Djokovic was gonna retire but I never want him to retire due to injury,” Nishikori joked.
“Federer and Nadal are strong too, but Djokovic is the most polished player."
Nishikori also praised compatriot Naomi Osaka for winning the last two Grand Slam titles on the women’s side of the draw.
"I'm surprised at how well Osaka can keep her calm while hitting aggressively,” he added.
“That reminds me of my young days, like when I reached the US Open fourth round at the age of 18. It's pleasant to watch her playing decisively, I want to play like that."