Zhang Shuai has stunned Wimbledon champion Angelique Kerber 6-1 2-6 6-0 in the China Open to set up a quarter-final clash with Naomi Osaka.
China's Zhang broke Kerber's serve five times and fired 22 winners to seal the victory in an hour and 27 minutes in her second meeting with the German.
"I can defeat a former number one, a Grand Slam champion, this is something I'm proud of for the rest of my life," an elated Zhang said.
The 29-year-old looked in complete control against Kerber, cruising through the first set before the German levelled the contest.
Yet Kerber struggled to keep her unforced errors count down, making 36 in the match, and her challenge ended in a final set rout.
Up next for Zhang is US Open champion Osaka, who thumped Julia Goerges 6-1 6-2 and described the performance as her best of the tournament so far.
"I know I played well today, better than all the other days," Osaka said. "Key today was staying focused and trying to return well because we both have really good serves."
Zhang has a 2-2 win-loss record against Osaka and beat the Japanese player in their last meeting in Madrid this season.
China's Wang Qiang advanced with a 6-4 6-4 win over world number seven Karolina Pliskova in an hour and 37 minutes while Kiki Bertens of the Netherlands crashed out after a 6-4 6-3 defeat by Katerina Siniakova.
Australian Open champion Caroline Wozniacki clinched a place in the season-ending tournament alongside Petra Kvitova after beating Estonia's Anett Kontaveit 7-5 6-4.
The in-form Aryna Sabalenka knocked out defending champion Caroline Garcia 5-7 7-6 (7-3) 6-0.
