BEIJING, China - US Open champion Naomi Osaka rallied from a set down - and from 1-4 in the final set - to see off Zhang Shuai and reach the semifinals of the China Open, 3-6, 6-4, 7-5.

"She's such an incredible player and it was really hard to play against her here," Osaka said on-court after the match. "I'm just thinking one match at a time, and it can only get harder from here."

With the win, Osaka makes more history for Japan, becoming the first woman from her country to reach the semifinals at the China Open since the event's inception in 2004.

Later, in her post-match press conference, Osaka added: "It's one of those moments where you don't feel your best, but you also -- I mean, you have to play. Both of us were trying our best. It was just one of those things that I had to find a way how to push through."

Despite accumulating 66 unforced errors over the course of two hours and 33 minutes, Osaka found her best tennis in the crucial points of the match to reach her sixth quarterfinal of the season.

The No.8 seed hit 51 winners to Zhang's 13, hit nine aces and broke serve six times to advance to a meeting with Anastasija Sevastova.

Zhang looked on course to score her second victory over the Japanese No.1 this season, having also beaten her on clay at the Mutua Madrid Open this spring, and started strongly in her biggest match on home soil.

The World No.45 broke serve twice and won the first three games of the match, and added her third break of six total in the match to wrap up a one-set lead.

She earned the opener despite hitting just two winners and eight unforced, as Osaka accumulated 22 unforced and served at under 50 percent. 

"I stopped thinking about winning or losing too much. I just thought that the way I'm acting right now, I'm probably going to regret it if I don't change it," Osaka said about turning around the deficit.

"I just tried to think, like, one point at a time, just try to be grateful that I'm playing."

A pair of lengthy games also went Zhang's way to begin the second set, as she saved six break points across seven deuces in a marathon opener, before breaking the US Open champion once more to lead, 6-3, 2-0.

After hitting 14 winners in the first set, Osaka hammered 22 in the second, and saved five of the six break points she faced.

Crucially, two of those opportunities came in the sixth game where she eventually held for 3-3, before winning three of the last four games. 

"Even if there's a small thing that I can do - or even to just put one more ball over, if it changes the outcome of the rally or the outcome of the match, then I'll do it," Osaka added.

"I just try to stay as focused as I can, which I didn't really do that well today, but it's something that I'm working on."

Looking to reach her fourth final of the season, Osaka will look to defeat the US Open semifinalist Sevastova for the second time in an upcoming third career meeting.

"I've played Sevastova twice, and both were on hard courts. I know that she's a great player. Everyone knows this. It's like at this round, of course you have to be good," Osaka assesed of the Latvian.

"I'm expecting a really hard match. I know that she's going to fight really hard. I didn't even notice until yesterday that I've never won a round here. Hopefully I keep the momentum."