A foot injury forced Emma Raducanu to retire from the Korea Open quarter-finals on Saturday, while third seed Beatriz Haddad Maia beat sisters Polina and Veronika Kudermetova on the same day to set up a Korea Open final clash with top seed Daria Kasatkina.
Former U.S. Open champion Raducanu struggled to serve with her injured left foot, as she played on after a medical timeout, committing a double fault and not chasing returns across the court.
The 21-year-old Briton retired after losing the first set 6-1 to Kasatkina.
The foot injury had also surfaced during Raducanu's round of 16 clash with Yuan Yue of China, when she was able to continue after a medical timeout and went on to win 6-4 6-3.
"I feel sorry for Emma... It's a pity to get injured, especially in the deeper stages of the tournament," Kasatkina said after the match. "I wish her a speedy recovery."
Kasatkina took to the court again later on Saturday, playing twice due to rain washing out Friday's play in Seoul. She beat fellow Russian and fourth seed Diana Shnaider 6-3 6-4 in the semis, as an exhausted Shnaider struggled with an injury.
Shnaider, who beat Ukrainian fifth seed Marta Kostyuk in the quarter-finals hours earlier, took a medical timeout in the second set of the semi before losing three games in a row as Kasatkina progressed to the final, where she will meet Brazil's Haddad Maia.
Haddad Maia, who brushed aside lucky loser Polina 6-2 6-1 in the last eight earlier in the day, defeated the elder Kudermetova sister and former French Open quarter-finalist Veronika 6-4 6-4 in the semis.
"I improved a little bit from the first match I had today so I'm happy," U.S. Open quarter-finalist Haddad Maia said after reaching her second final of the year. "Tomorrow I have another opportunity to do it better."