Zhang Shuai credits coach Liu Shuo for frequent success against Naomi Osaka

WATCH: Zhang scored her third win in six meetings with Naomi Osaka, who exited in the first round in Cincinnati.

Zhang Shuai can't explain why she's so good at playing against Naomi Osaka, but she showed it once again, taking down the four-time Grand Slam champion, 6-4, 7-5 at the Western & Southern Open in Cincinnati.

The 33-year-old from China has won three of their six meetings, even though her highest ranking of No.23 and three singles titles pales beside Osaka's haul.

"I just go be natural when we on court. Sometimes we taught to do something you don't like or you're not normally doing," Zhang told press at Cincinnati. "What you practice, you just go really natural."

It also helps to be used to Osaka's level of power, adds Zhang.

“Maybe her ball is strong, or maybe because I always hitting with my coach [Liu Shuo], man, much bigger. So, it's totally different,” Shuai said.

Against other players on tour, though, she says she's had more success when she hits with other WTA players, who don't smack it as hard but allow her to get more familiar with what she faces in competition.

...when I play against Simona [Halep], she always wins the tournament. I'm so good, like [for] them [to] get feeling. Zhang Shuai on her success as a hitting partner

“That's why when my coach goes back to States, when I'm in Nottingham, Birmingham [where she reached the final] every day hitting with Bia [Beatriz Haddad Maia, who won the tournaments], I feel like, 'Oh, different'... and then I play perfect two weeks," said Zhang, noting that it also seems to be good for the other player.

"Also Bia's, that's why I'm the best woman hitting partner for her!

"Also, when I play against Simona [Halep], she always win the tournament. I'm so good, like [for] them [to] get feeling.”

Zhang wasn't that happy with serving against Osaka, though her stats were good—but more importantly, she got the win.

“Sometimes you're feeling good, number looks no good. But the goal always is to win the match. If we won, yeah, that's the best,” said Zhang. “After win the match, always feeling better and better. More confident. That's the tennis."

Zhang is ranked No.44 in singles, and No. 2 in doubles on the WTA Tour.