British number two Emma Raducanu retired from her Korea Open quarter-final against Daria Kasatkina with an injury to her left foot.
Raducanu struggled with the issue in the previous round against Yue Yuan and continued to look uncomfortable in the opening exchanges against the Russian top seed.
The 21-year-old was broken in the second game but, despite breaking straight back, struggled to serve and was unable to chase returns around the court.
She needed a medical time out after the fifth game and decided she could not continue after losing the opening set 6-1.
Kasatkina will play compatriot Diana Shnaider in the semi-finals after she beat Ukraine’s Marta Kostyuk 7-6 6-3.
The match will take place later on Saturday after rain postponed play on Friday.
“I feel sorry for Emma,” said Kasatkina after the match. “It’s a pity to get injured, especially in the deeper stages of the tournament. I wish her a speedy recovery.”
Raducanu had been hoping to reach her first semi-final above WTA 250 level since her 2021 US Open victory.
The world number 70 has sustained a number of injuries since her Flushing Meadows triumph.
She was restricted to just nine matches in 2023 due to having surgery on both of her hands and left ankle.
Raducanu returned at the start of this year and reached the second round of the Australian Open, before skipping the French Open to focus on her fitness.
She reached the fourth round at Wimbledon to return to the world’s top 100, but suffered a first-round defeat by American Sofia Kenin at last month’s US Open.
