Japan's Yoshihito Nishioka comfortably advanced to the Australian Open second round with a 6-4, 6-2, 7-5 win against Sweden's Mikael Ymer on Monday.
The 31st-seeded Nishioka converted six of his 12 break point opportunities as he put away the world No. 69 in two hours and 18 minutes.
In other action from the first round at Melbourne Park, Japanese qualifier Yosuke Watanuki was victorious in his Grand Slam singles main draw debut, beating Frenchman Arthur Rinderknech 6-3, 6-3, 6-2.
In the women's draw, Japan's Moyuka Uchijima exited with a 2-6, 6-3, 6-1 loss to Bernarda Pera of the United States.
Japan's highest-profile men's and women's players are both absent from the first Grand Slam tournament of the season.
Kei Nishikori remains sidelined following an injury to his ankle, while two-time Australian Open champion Naomi Osaka is expecting a baby and has indicated she will return to the court next year.