The Czech saved three match points when Barty served for the match at 5-3 in the decider but the Australian fought back to deuce and then fired a crosscourt forehand victor to move into the tournament's semis for the first time in her career.
It was also the Canadian's first loss to a top-10 opponent in nine matches. Serving for the triumph, the Aussie seized the fourth match point with a forehand victor to seal the deal and advance into the semi-final, just like in Wuhan last week.
"I'm glad it was entertaining for everyone. I think that it kind of lived up to the hype".
Osaka nailed the third match point with an ace, her 11th of the match.
But Osaka, the Australian Open champion and a former number one, powered back to make it 5-5.
"I feel like I play very well here". "Thankfully, that's what happened".
In the semi-finals will take Beijing, even a year ago in the final four in Beijing, and it's on at the Danish titelverdedigster Caroline Wozniacki (WTA 19).
The other semifinal of the WTA Premier-Mandatory event pits top-ranked Ash Barty of Australia against No. 8 seed Kiki Bertens of the Netherlands.
"From my opinion, that was one of the highest quality matches I played all year", said Barty, the French Open champion.
"That's always a challenge, trying to be assertive and get free points without giving Petra a bunch of looks at second serves".
Barty had 31 winners and 20 unforced errors while Kvitova counted to 36 winners and 28 mistakes, battling hard from start to finish with aggressive and attacking tennis.
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