BEIJING, China - US Open champion Naomi Osaka made a winning return to the courts at the China Open on Monday, as she defeated Kazakhstan's Zarina Diyas in first round action, 6-4, 6-3.

After her maiden Grand Slam win in Flushing Meadows, Osaka reached the final of the Toray Pan Pacific Open on home soil before losing to Karolina Pliskova, but was forced to withdraw from the Dongfeng Motor Wuhan Open last week due to a viral illness.

The No.8 seed broke the Kazakh qualifier five times in the match overall, as the World No.91 accumulated 19 unforced errors to just seven winners over the course of 68 minutes of play. 

"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," Osaka revealed after the match.

"I feel like playing against her, I've played her before in French Open, and it was a really tough match. I think I needed to find a way to win, even if it was playing ugly or not."

After an opening set that went with serve for the first eight games, Osaka claimed the lone break in the penultimate game en route to a one-set lead, and outlasted the Kazakh in a back-and-forth second set.

The first three games were breaks of serve, before the Japanese No.1 seemingly pulled away by winning four straight games from 1-1.

The qualifier nonetheless made her work for the victory, as she earned a second break of serve in the set when Osaka first served for the match, only to surrender her own for the fourth time in the set to be defeated.

Osaka totaled 12 winners to 14 unforced in the match overall, and won nearly 70 percent of the points played on her first serve despite landing under 50 percent of them for the match.

"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," she said. 

"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."

Up next for the 20-year-old is American Danielle Collins, who took out former Top 10 player Timea Bacsinszky in the first round on Sunday in three sets. 

In other action in Osaka's section of the draw, No.10 seed Julia Goerges advanced to the third round when US Open quarterfinalist Lesia Tsurenko was forced to retire with a back injury with the match evenly poised in the deciding set, 6-4, 4-6, 2-2.