Britain’s Emma Raducanu defeated Belgium’s Yanina Wickmayer 6-3 7-5 to progress to the Korea Open last eight in Seoul.
Raducanu, ranked 77th in the world, broke Wickmayer’s serve three times in a row at the end of the first set to seal the opener.
A cagey second set ended with Raducanu breaking once more, after being taken to deuce in the previous game.
The 19-year-old will play Poland’s world number 51 Magda Linette next.
Victory over Linette would be the first time Raducanu has won three matches in a single tournament since her extraordinary run to the US Open title in September 2021.
World number 460 Wickmayer, who was ranked as high as 12th in the world before taking a break for the birth of her first child in 2021, grew into the match and threatened to take the contest to a decider.
But Raducanu, who has been working with Russian coach Dmitry Tursunov since July, kept her composure and consistency to see out the win.
Elsewhere, defending champion Naomi Osaka withdrew from the Pan Pacific Open in Tokyo because illness.
The 24-year-old was due to play Brazil’s Beatriz Haddad Maia in the second round.
“This has and always will be a special tournament for me and I wish I could have stepped on court today, but my body won’t let me,” she said.
The four-time Grand Slam winner, who has slipped to 48th in the world, had won only one of her previous seven matches before arriving in her native Japan. Her first-round victory over Daria Saville came after the Australian tore knee ligaments in their match on Tuesday.