Australians Nick Kyrgios and qualifier James Duckworth have won their opening-round matches at the Japan Open in Tokyo.

Sixth-seeded Kyrgios has scored a comfortable 7-5 6-2 victory over American Ryan Harrison to set up a round-of-16 clash with Radek Stepanek of the Czech Republic. The veteran Stepanek had earlier beaten Frenchman Stephane Robert 6-2 6-1.

The unseeded Duckworth had been locked at a set-all and leading 4-2 against eighth-seeded Feliciano Lopez, before the Spaniard was forced to retire. The young Australian eventually prevailed 6-7 (5-7) 7-6 (7-4) 4-2.

Duckworth will face Juan Monaco in the round of 16. The Argentine earlier defeated Taylor Fritz of the United States 7-6 (7-2) 7-6 (7-5).

In other Tuesday first-round action, Czech Jiri Vesely downed Kevin Anderson of South Africa 3-6 6-0 6-4, and No.5 seed David Goffin of Belgium accounted for local player Yoshihito Nishioka 7-5 6-2.