New York, Sep 2 (IANS): Third-seeded Japan's Naomi Osaka advanced to the third round of the US Open as her opponent Olga Danilovic withdrew due to illness.

Said Serbian qualifier Danilovic on Instagram, "I have been feeling unwell these past few days dealing with a non-COVID-related viral illness."

"I am so sad to have to withdraw from my match this morning. I was really looking forward to playing against Naomi on Arthur Ashe Stadium today, but not to be this time." the 20-year-old was quoted as saying by Xinhua.

The 23-year-old Osaka will now face Canada's 73rd-ranked Leylah Fernandez.

Earlier, the world No.3 had kicked off her US Open title defence with an impressive win over Czech Republic's Marie Bouzkova 6-4, 6-1 in the first round.

The two-time US Open champion had fired 34 winners to 24 unforced errors to break down Bouzkova's defensive game in the first set and then ramped up the pressure to win the second set with ease.

Osaka had been in the middle of controversy in recent for refusing to speak to the media. She had withdrawn from the French Open and Wimbledon citing mental health issues.