Naomi Osaka returns ball to Karolina Pliskova during the Pan Pacific Open Women's singles final match at Arena Tachikawa Tachihi, Tokyo, Japan, on September 23, 2018. (Photo: Reuters)

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The No. 8 seed had a tough outing against Kazakh player Zarina Diyas but managed to win 6-4, 6-3. Osaka fired out 4 aces and 12 winners against 14 unforced errors, while Diyas had only 7 winners to 19 unforced errors.

The young Japanese star recognised that she did not deliver a complete performance.

"Well, I mean, I felt like today was pretty rough. I know that I didn't play that well, but I really wanted to win. I felt that she probably didn't play at her best, too. I think we were both just trying to struggle with how to manage the situation."

Looking forward into the tournament, Osaka is confident she can find a way to improve her game and play to her potential in Beijing.

"I feel like overall, like even during practices, I still haven't hit the ball cleanly, like I want to. That was a concern going into the match. Then I felt like I didn't serve well today at all. I think my first-serve percentage was probably ridiculously low...for sure that's one thing that I want to fix going onto my next match."

Osaka's next match is against the USA's Danielle Collins in the round of 32.

In the men's draw, a visibly frustrated Sam Querrey lost 6-4, 6-4 to Karen Kachenov.

No. 2 seed Caroline Wozniacki thundered past Switzerland's Belinda Bencic 6-2, 6-3.