Naomi Osaka starts life as US Open champ with win, Garbine Muguruza dumped out

Naomi Osaka celebrates

Naomi Osaka looked every bit the US Open champion as she beat Dominika Cibulkova in straight sets at the Pan Pacific Open.

Less than a fortnight after winning her maiden Grand Slam, the third-seeded Osaka breezed into the quarter-finals in Tokyo with a 6-2, 6-1 win over the Slovakian in an hour.

The 20-year-old raced into a 4-0 lead in the opening set after breaking twice and then won six games in a row in the second set to ease to victory.

Sixth seed Garbine Muguruza crashed out as the two-time Grand Slam winner suffered a 6-1, 6-2 drubbing at the hands of qualifier Alison Riske from the United States.

Next up for Riske is Karolina Pliskova after the fourth seed beat Daria Gavrilova from the Australia 4-6, 6-4, 6-4.

Meanwhile, second seed Caroline Garcia overcame a second-set slump against Anastasia Pavlyuchenkova, winning 6-4, 2-6, 7-5.

Top seed and two-time defending champion Caroline Wozniacki will kick off her campaign for a third title against Camila Giorgi on Thursday.

More from Tennis365: