US Open champion Naomi Osaka fought back tears and rallied from a set down to outlast Zhang Shuai 3-6, 6-4, 7-5 in the China Open quarter-finals on Friday.
Japan's Osaka struggled to find her rhythm throughout the contest, making 66 unforced errors, and had tears in her eyes midway through the second set with the match slipping away.
She fought back, however, and eventually proved too strong for her Chinese opponent, prevailing in two hours and 33 minutes.
"She is such an incredible player and it was really hard to play against her here. I'm just thinking one match at a time, and it can only get harder from here," said Osaka, who cried following her US Open win that was overshadowed by Serena Williams' altercation with umpire Carlos Ramos.
Zhang raced into an early lead and held firm to clinch the opening set comfortably. The 29-year-old went 2-0 up in the next to raise hopes of an upset victory.
Osaka battled with her emotions but held her nerve to save two break points before dragging the contest into a decider.
Zhang, however, refused to back down and went up 4-1 before Osaka switched gears to close out the victory.
"I was sort of apologising for my behaviour because I was kind of stressed," Osaka said when asked what the pair spoke about at the net following the match.
The 20-year-old will next face Anastasija Sevastova. The Latvian beat Dominika Cibulkova 6-3, 7-6(5).
Caroline Wozniacki later thumped Katerina Siniakova 6-2, 6-2.
"I think I played really well, probably the best match for me in the tournament. It's exciting to feel like I'm playing well at the end of the year," world number two Wozniacki said.
The Dane next faces Wang Qiang who overcame the in-form Aryna Sabalenka of Belarus 7-5, 7-5.