The No 6 seed, Russian Diana Shnaider, advanced to the semi-finals of the Tokyo Open after Japanese qualifier Sayaka Ishii withdrew before their match on Friday night at the Ariake Coliseum.
Shnaider, ranked No 16, will face the winner of the match between top seed Chinese Qinwen Zheng and No 8 seed Canadian Leylah Fernandez next.
In the previous round of the Tokyo tournament, the 20-year-old Russian defeated Bulgarian Viktoriya Tomova (6-2, 6-2).
Ishii, ranked No 279, had victories over lucky loser Sara Saito (6-1, 6-1) and qualifier Zeynep Sonmez (4-6, 6-2, 6-3) earlier in the tournament.
Results of other matches in the last eight of the Tokyo WTA 500 (Ariake Coliseum, hard, USD 922,573, with the most recent results listed first):
- Qinwen Zheng vs. Leylah Fernandez
- Sofia Kenin (WC) defeated Daria Kasatkina (3) with a score of 6-3, 6-4
- Katie Boulter (9) beat Bianca Andreescu (WC) with a score of 6-2, 6-1
