Chinese wildcard Guo Hanyu pulled off an almighty comeback to knock out 12th-seeded Romanian Sorana Cirstea 1-6, 7-6 (8/6), 7-5 in the Wuhan Open first round on Tuesday.
Guo, a doubles specialist ranked 240 in the world in singles, entered the match searching for just the third tour-level victory of her career.
The 28-year-old Zhengzhou native rallied back from a set and 0-4 down against Cirstea, saved three match points in the second-set tiebreak, and erased a 3-5 deficit in the decider to complete the upset in two hours and 41 minutes.
A tearful Guo later revealed to Chinese media that she was spurred on by her ailing father, who has been "seriously ill" and in since July.
"Knowing this actually made me feel quite helpless," said Guo.
"No matter what kind of efforts you make, I'm struggling recently because mentally, psychologically I always feel something. I cannot just have a happy moment on the court and enjoy the game. I will always have a kind of sorrow, so that's why I made a lot of efforts today.”
Guo will next take on American world number 88 Katie Volynets for a place in the round of 16.
Meanwhile, Marta Kostyuk’s chances of qualifying for a maiden WTA Finals dwindled on Tuesday as the world number 10 crashed out of the second round 4-6, 6-2, 6-2 to Maria Sakkari.
Kostyuk is in the running for one of the two remaining qualification spots in the eight-player field at next month's season finale in Indian Wells but needed a strong showing in Wuhan to strengthen her odds.
The 35th-ranked Sakkari, who is making her first singles appearance in Wuhan since 2018, produced some of her best tennis in her opening two rounds, and will face one of two wild cards, Wang Xiyu or Mia Pohankova, in the last 16.
"The base of my game is there. It's just about trying to be a little bit more brave in the big moments," said the Greek former world No 3.
American Ann Li booked a second-round meeting with top-seeded Aryna Sabalenka after her Colombian opponent Camila Osorio retired with a lower back injury while trailing 6-1, 3-0.
Former French Open champion Jelena Ostapenko handed qualifier Daria Kasatkina a brutal 6-1, 6-1 defeat to set up a clash with last year's runner-up and Wuhan second seed Jessica Pegula.