Coco Gauff said online racist abuse had left her feeling exhausted after she went out of the China Open with her loss to Elise Mertens on Wednesday.
The American world No 4, who is Black, turned in an uncharacteristically listless performance in Beijing, double-faulting eight times as she went down 6-3, 6-3 to her Belgian opponent.
Gauff, 22, was playing a day after she called out the "insane" amount of abuse she had received on the internet following her win over Chinese teenager Sun Xinran in the previous round.
"It has been kind of draining. I'm not going to lie," Gauff said of the impact of the online comments.
"But I just turn off my phone and move on. There's nothing you can do."
Asked about the match, she said: "I think I just didn't play well. I think I wasn't moving well.
"There were a lot of things I didn't do well. I thought Elise played well on the bigger points."
During her previous match in Beijing, against Sun, Gauff requested a video review over flickering LED lights on the stadium's advertising hoardings.
The move prompted some boos from the crowd. The umpire agreed to have the point replayed, and Gauff went on to win 7-5, 6-1.
Early on Tuesday, Gauff wrote on X: "Hey everyone, you can dislike me or disagree about what happened without being racist."
She was responding to a post that contained a racial slur.
"The amount of racist comments and messages I've received in the last few hours is insane," she wrote.
Gauff also clarified that she challenged the point before Sun had returned the ball, when she noticed the lights flicker for a second time.
Asked about the incident, a spokesperson for the Women's Tennis Association, the global governing body, said they were "appalled by the racial abuse directed at Coco Gauff and are in contact with her to offer our full support".
It added in a statement to AFP that there was "no place for racism, discrimination, or abuse in tennis", and that it was "seeking action" against the abusive content.
Gauff, who won the Beijing title in 2024 and made the semifinals last year, is a popular player among fans at the tournament itself.
A group of supporters in the largely empty stadium tried to encourage her into a comeback on Wednesday.
Hours later, the Wuhan Open said Gauff had withdrawn from the prestigous 1000-level tournament "citing fatigue".
"I'm disappointed to withdraw from Wuhan, especially as the defending champion. I always love playing there," Gauff said in a statement shared by the tournament on Instagram.
"After a long year, my body needs some time to rest and recover. I look forward to returning next year," Gauff said.
The Wuhan Open runs from October 12 to 18 in China's central Hubei province.
'ALL TOO FAST'
Mertens was undeterred as she punched her ticket for a quarterfinal clash against Iga Swiatek.
The world number 19 called Gauff an "incredible player", adding: "I knew it was going to be a very tough match".
She dedicated her win to her coach, who is also her boyfriend.
Earlier, Swiatek swept aside American teenager Iva Jovic 6-1, 6-3 in one hour and 35 minutes.
In the night session, China's Zheng Qinwen pulled off another three-set victory to dispatch Alina Charaeva 6-1, 2-6, 6-4, ending a breakout week for the 118th-ranked player in which she beat freshly minted world No 1 Elena Rybakina.
The match was not without disturbance, though, with Zheng gesturing with her racquet towards shuffling spectators during the second set, and the umpire stopping play during the third to replace a broken hook for the net.
"I started pretty well... but maybe during the second set I think I felt myself decline, also with the temperature getting colder and colder and the ball speed dropping," Zheng said afterwards.
"I'm really grateful," she told the crowd, tearing up as the on-court interviewer reminded fans it was the day before Zheng's 24th birthday.
"All I can say is that it's all come too fast," Zheng said, smiling as the crowd wished her "happy birthday" in unison.
Zheng, the current world number 54, will face Ukraine's Elina Svitolina, the sixth seed, in the quarterfinal.