Top seed Iga Swiatek reached the round of 16 of the China Open on Monday, but her victory came in disappointing fashion as Camila Osorio retired with an abdominal injury after dropping the first set 6-0.
Despite the lopsided score, the opening set was competitive, with five of the six games going to deuce.
Trailing 5-0, the Colombian took a medical time-out, but after falling 0-40 on her serve in the second set, she was forced to withdraw.
The world number two will face Emma Navarro, who also advanced after her opponent, Lois Boisson, was forced to retire due to injury.
Navarro had already stamped her authority on the match, breaking serve within the first three games to take control. The American, ranked world number 17, never allowed Boisson back
into the set, holding serve comfortably and creating another break opportunity at 4-2, before serving out the opener clinically, sealing it 6-2 before Boisson's retirement.
Emma Raducanu squandered three match points and dropped her fourth consecutive tiebreak, falling 6-3 6-7 0-6 to Jessica Pegula.
Raducanu started strongly by going 3-0 up in the first set, but her profligacy in the second ultimately cost her, as Pegula went on to cruise in the third to secure a round of 16 spot.
Pegula will face Anastasia Potapova in the next round, after the world number 59 saw off Zeynep Somnez 6-3 7-5.
11 - Including retirements, only Madison Keys (16) has won more three-set matches at WTA level in 2025 than Jessica Pegula (11). Big.#ChinaOpen | @ChinaOpen @WTA @WTA_insider pic.twitter.com/QfStzHVwgh
— OptaAce (@OptaAce) September 29, 2025
Elsewhere, Mirra Andreeva beat Jessica Bouzas Maneiro in straight sets, 6-4 6-1, but was forced to fight back after the Spaniard broke serve early in the first set to initially take the lead.
In the second, Andreeva reeled off five consecutive games to ease into the round of 16, where she will meet Brit Sonay Kartal.
Data Debrief: Swiatek makes history in China
Swiatek's 6-0 first set marked her 17th such set of 2025, the most on tour this season - 10 more than second-placed Ekaterina Alexandrova, who has claimed seven 6-0 sets.
The world number two has become the first player since the China Open began in 2004 to win her opening eight matches in the Women's singles draw.
Raducanu has now lost nine matches in a row against top-10 opponents, a run that stretches back to her Miami Open quarter-final defeat to Pegula in March.