British number one Katie Boulter suffered a straight-set defeat by top-ranked Aryna Sabalenka in the second round at the China Open.
Boulter was beaten 7-5 7-6 (7-2) by Australian Open champion Sabalenka.
That was despite Boulter, 27, serving for both sets when leading 5-4.
Sabalenka, runner-up at the US Open in September, fought back to take the first set before the Belarusian sealed victory by winning six successive points in a dominant tie-break display.
World number one Sabalenka will face Italy's Jasmine Paolini for a place in the quarter-finals.
"I definitely left everything I had on the court," Sabalenka said. "She played unbelievable tennis, I'm super happy that I was able to win this match."
American world number three Coco Gauff and compatriot Jessica Pegula both also progressed in Beijing.
US Open champion Gauff, 19, prevailed in a third set tie-break against Croatia's Petra Martic, clinching her first match point to seal a 7-5 5-7 7-6 (7-2) victory.
"I was just trying to play every ball. She raised her level and she was playing really well," Gauff said after extending her winning streak to 14 matches.
"I didn't play my best the whole match, but the tie-breaker was definitely my best. These matches are going to make me tougher for the rest of the tournament and the rest of the season."
Fourth seed Pegula came back to defeat Russian Anna Blinkova 6-7 (2-7) 6-2 6-1 and set up a meeting with Latvia's Jelena Ostapenko.
However, Wimbledon runner-up Ons Jabeur was knocked out by Ukrainian 21-year-old Marta Kostyuk.
Tunisian seventh seed Jabeur was broken when serving for the first set at 5-4 and, after falling short in the tie-break, managed to win only one more game as Kostyuk, ranked 33, wrapped up a 7-6 (7-5) 6-1 victory by winning the final five games.
The Women's Tennis Association decided to resume tournaments in China this year after accepting an investigation will not be carried out by the Chinese government into sexual assault allegations made by former player Peng Shuai.Live scores, results and order of playAlerts: Get tennis news sent to your phone