Home favourite Kei Nishikori advanced to the second round of the Japan Open after a 6-4, 6-1 win over compatriot Yuichi Sugita on Monday.
The world No. 11 has not won an ATP Tour title since 2016 but has enjoyed recent success in the competition after lifting the title in Tokyo in 2012 and 2014.
"I always enjoy playing in Japan. It's something special," Nishikori told the ATP Tour's official website ahead of the tournament. "It's only once or twice, a couple times a year I get to play in Japan, so I always enjoy it. I hope I can enjoy this whole week."
Nishikori will play Benoit Paire in the second round after the Frenchman defeated Nicolas Jarry 6-4, 7-6(1).
No. 4 seed Diego Schwartzman was the biggest name to fall in the first round, losing 6-4, 6-4 to Russia's Daniil Medvedev.
Milos Raonic, who is also without an ATP title since 2016, defeated Adrian Mannarino 6-3 6-4. The No. 6 seed will play Japanese qualifier Yosuke Watanuki in the next round after he beat Robin Haase 6-7(7), 6-4, 6-1.
Denis Shapovalov defeated No. 7 seed Hyeon Chung 6-3, 3-6, 6-2 while Martin Klizan beat American Steve Johnson 6-4, 7-6 (4).